First of all, I want to make clear that rating is really difficult for me. I know I can tell sh*t from gold, but that's about it.
Anything with less than 2.5* is, IMHO, a waste of time. I randomly rate series I don't like from 1* to 2*, but beware of 0.5* because those are the worst turds I've ever seen.
What about the good stuff? Well, this would be my ideal rating:
I try to stick to this, but I've caught myself rating poorly a good series just because I hate the MC or giving a good score to a crappy series because I was in a good mood.
That's all. It really makes my day when I find good anime, so I hope my list can help some of you to find something new.