Welcome here Havva.
Merely offering a good RP corp or group for a Minmatar character is not as easy is it sounds, there are many options, none are limited to being Minmatar - it depends what you want ot do.
Republican loyalist - the Electus Matari, among others, is an alliance by Minmatar for Minmatar (mostly, many others there too) who endeavor to protect the Republic from all dangers, internal or external, iirc.
Minmatar Freedom Fighter - many, many options, among them the new form of Ushra'Khan, (sorry can't recall new name now) an alliance fighting to end slavery, situated in Providence last I looked. There are so many others, options really are grand.
Minmatar Terrorist - Havohej's corp (could not pronounce the name to save my life
) is on this category, the difference from a Freedom Fighter and a Terrorist is slim, mostly in the eye of the beholder, however actions define differences as well. Havohej's corp is quite extreme in their goals and methods and will differ from many other Minmatar outfits in rules of conduct.
Empire loyalist - A minmatar born a slave in the empire, or born a Nefantar (reffer to the Ammatar Free Corps in the CVA alliance for this branch - there are many others) who remain loyal to the Empire, either as a faithfull servant, or a slave freed by his/her master and serving of thir own will and faith, or many other options.
A pilot that left Republic space to join the State and assist the Caldari (See members of the I-RED alliance for this) are another option, as is...
Federation citizens, as the Gallente Federation is roughtly one third Minmatar who immigrated to it the option to join them and play a 'Federal Minmatar' is an ever available one. For this talking to Seriphy Inhonores might be wise, or Zagamesh, he played one for years until very recently.
Then there are the 'unlawfull' options like joining the Angel Cartel, Guristas, becoming a Blood Raider or siding with the Sansha's Nation. Reffer to Verone, Mishara, Aria Jenneth and others for these options.
Honestly the options are not in any way limited for a Minmatar character. Playing a minmatar is like playing a Gallente or anyone else - it has a spesific 'generalized' flavor that is then taken and modified until you have a character that suits you and your desires.
Look around these forums, and you will find what you need and others who can help you.
P.S: Here's your cup - *hand over a cup* someone will be around soon to fill it with coffee or tea, depending on your prefference.