Currently, the scout is widely regarded as the most underpowered of suit types. We have fewer fitting options and weaker defenses than any other dropsuit class, and there are those who claim that we have no remaining advantages at all.
These people are fools, and should be made to die on your knives as often as possible.
This is a guide for survival and success in this most underestimated, yet exhilarating, of roles. I will be starting with my own preferred tactics and fit, and invite Denak Kalamari to share his as well (it's similar, but built on a Gallente frame and with subtly different priorities. He's also both more experienced and better at it than I am).
Many will argue that the scout's role has been almost subsumed by the logistics suit. It's not true, but it's close. The single great, nigh-unique advantage that scouts possess is a potent skill-based stealth modifier. In all else-- firepower, speed, whatever-- we can be matched, or nearly matched, by something else, usually in the form of a logistics suit.
(Technically, we can also be nearly matched in stealth, with the right fit.)
And yet, for my money, the scout/infiltrator is the single most entertaining role on the field.
The scout/infiltrator is the "go there, get stuff done" suit. It's fast, it's quiet, and that's about all it really has to be. The rest is all gravy-- delicious, delicious gravy. So, let's get to it.
1. Much like Garrett of the "Thief" games, "YOU ARE NOT A TANK."
This cannot be emphasized enough. Unless you get lucky and run into a logi who's fitted a sniper rifle, every fight you get into will be a desperate one. It doesn't matter that you have a shotgun or that the hostile is in a militia assault fit; at best, that just puts you on roughly level ground, which you still don't want. It DOES matter if you can down them in a couple hits and have an automatic weapon-- but that's not really a fight, is it?
As a scout, that last is exactly the sort of fight you want: the sort that's over, in your favor, before it begins. Everything else is to be avoided-- which is a problem, because redberries tend to be damned persistent.
As a rule, if you are spotted, your top priority should be escape. "Escape," in this context, often will have to just mean that when you strike, it is with impunity for as long as it takes to make the target dead. This can mean looking straight down the barrel of a pursuer's assault scrambler, so long as the next sound out of your speakers is your remote explosive detonator saying, "beep."
You are not a front-line fighter, ever. If you need to throw your body on a problem, you'd be well-advised to switch to an assault suit first.
2. "Deaths for all ages and occasions!"
... or malicious pranks, at least. Somebody who's going to be going all over the map, which a good scout should be, needs to be prepared for what's out there. Sometimes that means fighting off a roaming LAV hell-bent on running you flat. Sometimes it means sneaking up on a sniper. Sometimes it means teaching a heavy some humility. Sometimes it means throwing caution to the wind and rushing to flank the guys who have the combat elements of your squad pinned down. Sometimes it just means scaring the hell out of a high-end tank.
What I'm getting at is that you cannot usually afford to have a lot of highly-specialized fits, except for your primary role, which is "mixed-media troublemaker." If you die out in the boonies or deep in enemy territory, it's going to be a long walk to get back. Try to give yourself a fighting chance against anything you can't run away from.
3. Stealth is your all. Do not give yourself away lightly.
Again, what can see you can probably kill you, so try not to reveal your position when you don't have to. Simple and problematic as that. Especially, when somebody stops and offers you a ride in their zippy but oh-so-obvious LAV?
Don't get in. Same with dropships.
4. You're a scout. Act like it.
A scout/infiltrator is a scout, not a lone wolf. Have a mic and relay interesting stuff you notice, whether it's in your vicinity or not. The rest of your squad is likely too busy killing people to notice, but tips like "Enemy hacking the eastern CRU; too far away for me to stop it" is pretty crucial information, as is "blaster Gunnlogi entering the city south of Alpha."
5. Skirmish is your bread and butter. It's also your oxygen.
You don't really want a match type where everybody is always concentrated in one area or where they have nothing better to do than look for stragglers to shoot (you're not technically a straggler, but you'll do just fine for target practice). You DO want a match type where you can make your sneaky self useful, and where people have important things to attend to that will have them turning their backs to the rest of the world for several seconds at a time.
Sample fit: "Minja" scout
This suit is the best example of the "mixed-media troublemaker" strategy I've been able to come up with to date. It's all about being able to cover a lot of ground quickly and quietly, and make a menace of yourself once you arrive.
Dropsuit: basic (if you can get it fitted satisfactorily) or advanced Minmatar scout.
Light weapon: shotgun. Quality matters minimally unless you're up against a heavy.
Sidearm: nova knives, advanced
Grenade: standard or packed AV grenades, whatever level your skill, fitting, and budget will bear
Equipment: remote explosives, advanced
High-power slots: shield extenders (this may change if CCP starts making these affect your profile)
Low-power slots: biotic upgrades - kinetic catalyzer x1 for sprint speed, cardiac regulator x1 to maintain it, advanced for preference
Strengths: scary-fast, gets everywhere before anybody expected it to be there. Quiet enough that few will see it coming, but hits tremendously hard. Able to give all infantry and most vehicle types a hard time at close range.
Weaknesses: weak against opponents it can't reach. Enemies on rooftops and in dropships are a problem + will generally have to be baited into descending.
* the shotgun is a backup and emergency weapon rather than primary ordinance. Its firepower is high enough to seem to invite direct confrontation, but the suit's weak defenses make that a risky tactic. Also, and never, ever, forget this: it's powerful enough to be feared and its sound is both highly distinctive and LOUD. You have very few shots before everybody in close proximity starts looking for the shotgunner.
* nova knives are a very powerful but somewhat tricky-to-use weapon. DUST's movement mechanics allow clone soldiers to backpedal nearly as fast as you can advance, so a backpedaling assault suit with an SMG will gun you down before you can close range. Also, the hit detection on retreating targets is dubious. However, they have a nice, wide attack that seems to cover at least a 90 degree arc in front of you; don't worry about that paranoid hacker zig-zagging away in front of the console.
* the knife attack is a very quick, but not instantaneous, one-two; you can hit one target with both, hit with one and miss with the other, or hit two separate targets. The results are occasionally hilarious.
* use advanced knives, charged, for best balance of economy and power. There's a huge difference between the tiers. Standard are too weak to bother with, advanced one-hit most targets if they're charged, and Ishukone (prototype) are overkill for most purposes unless you're using them uncharged. This may change with the coming armor upgrades.
* the nova knife is a true stealth weapon-- the only one in the game. Everybody turns towards the sound of a shotgun, but nova knives are all but silent. Few opponents will even understand what killed them for a few seconds if they get nova knifed from behind. Hackers and snipers are favorite prey. You can cut down whole sniper teams cozied up on a ledge, one after another.
* in planetary conquest matches, do not attempt to use nova knives if you have teammates within reach unless you want the most embarrassing team-kill ever.
* all of the above said, about half of your kills will come from the remote explosives. Using advanced cuts down their time to go "live" to about two seconds, which means you can use yourself as bait for a charging hostile rather than being restricted to using them as pre-set traps. Use them freely, ruthlessly, and creatively, and try to have some member of your squad carry nanohives so you can resupply if the supply depots get blown up.
* LAV drivers are arrogant so-and-sos. The AV grenades should let you kill the weak and drive off the strong without having to dodge around for more than a few seconds at a time (and you should develop dodging them to an art form as a matter of basic survival). Always remember that an AV grenade on the ground is still active for several seconds, so you can bait aggressive drivers into running over them. You can use RE's this way, too, but the blast is hard to time manually.
* in combination, the AV grenades and remotes are potent against tanks. The forge gun may be the game's premier AV weapon, but nothing beats the shock value (or the alpha strike) of three remote explosives going up under a tank all at once. They can one-shot a militia tank, and even experienced players are often astonished at the damage output. If you use them to supplement other AV an advanced tanker was just shrugging off, and then start hucking grenades, you may find yourself with a kill WAY above your weight class.
Comments and critiques are, of course, welcome. I will be modifying and adding to this topic over time.