On my return to Eve (3rd time's a charm) last year I first got into some research, I wanted to try something I'd never done before. But I didn't make the same mistake I'd made previously, in that I burnt myself out on the primary activity and thus the game as a whole, so instead of just focusing on research I also stuck my toes into the pond that is trading, and manufacture, all while still running missions with a few friends.
Honestly, the biggest piece of advice I can give anyone trying this game, for the first or nth time, is DO NOT TRY TO FOCUS ON ONE ACTIVITY. Sure, have an idea of what you enjoy and do that most, but mix things up a bit, don't get locked into the same activity for 3 hours every time you log on or very quickly the game will grow stale.
The seconds biggest piece of advice I can offer is, play with friends, or if there are none available, make new ones in game. Everything, even the most boring task, is enjoyable if while you're doing it you can also half a laugh and a chat with your friends who're there doing it with you.
Right now I'm living in a worm hole and for the past 5 months have been paying for the game through in game means by shipping out the Sleeper salvage and selling it in empire space, then buying a plex when needed. It's going really well, and I'm finally getting into reverse engineering and will likely start construction of T3 ships in the near future.