I don't know the system well enough to use Mids, so I generally just wing it. I might look at a build online, but as OP pointed out, it's rare to find ones that aren't purpled-out endgame builds.
I mostly solo and just run regular missions.
I use SOs until level 20 or so, then switch to generic IOs, which I replace every 10-15 levels. If I'm having trouble with endurance, I might throw a proc in Stamina. If I feel like it, and have Inf to burn, I might throw a few sets in random powers. No idea what I'm doing.
Most characters get retired at level 50. I have one character, a Mace/Shield Brute, that I dragged through the Incarnate system long enough to put something in each of his slots. Wasn't much fun, though, so I probably won't do that again. Since I put so much work into him, I pull him back out occasionally to see how many badges I can get for him.
Basically, I'm about as lazy/casual as you can get.