just have to get a soil mix that drains well and holds a little moisture throughout the cup or pot, evenly.. the mix I have now (after testing out a bunch of different mixes, the one I have now I like so far) but I water it until it drains from the bottom, which is pretty quickly, but there is enough moisture being held in all the soil, just not soaking wet, just damp
I like top watering just because I know I can get all the soil damp, and at least with the gallon pots in the grow tent... I can't/won't flood the entire bottom of the tent, because then it would be a huge PITA getting the excess out.. and I'm not taking 80+ plants moving them around and dipping them into water every 5 days or so.. just too much for nothing.. and those little saucers things on the bottoms that you can put under the pots cost like $0.75 or maybe $0.50 up here, but either way... $40 for those is a bunch of crap lol, so I like my top watering.