So… the best piece of advice I can give you is, “don’t look for a good corporation… look for good people.”
By this I mean; go out there and just do stuff. Meet people along the way, get to know them.
Even if the people you talk with don’t do exactly what you are looking for, they can lead to other connections down the road.
For you, since you mentioned Merc and PvP stuff, I would suggest doing some random forays into low-sec.
Look for some cheap fights, get some laughs out of people, see if you can kill someone, talk with the people you fight against.
Those connections eventually do go somewhere.
edit: It occurred to me that I should explain the low-sec thing.
Low-sec is one of those places where, in order to survive, inhabitants have to “diversify” their income.
Quite often, you’ll have PvP groups that do some combination of Faction Warfare plexing/missioning, module and frigate production (for Faction Warfare), Moon Goo harvesting, Mercenary/Ganker contracts, Planetary Interaction, and even capital industrial manufacturing.
And most of the longer-lived groups in low-sec are on a “first name basis” with each other… even their enemies.