I tend to prefer female singers and I care more about a charismatic/beautiful/interesting voice than actual singing skills.

I tend to take my time to go through artist's discographies, even for those artists I rather like (for those I prefer to own the albums first before listening to them). I go through their discographies quite slowly, maybe a bit too slow ... (something I do want to change, actually)

I haven't really worked out a good system behind my ratings yet.

For now: I don't tend to listen music I know I will probably dislike, so you won't really find many ratings below 2 stars. I'm not very generous either.
3 stars means I did enjoy the album, but that it bores me at some points. 3,5 stars is a good album throughout. 4 stars is a great album. 5 stars is a desert island disc.
tl;dr: < 3 meh; > 3 I like it

Unrated albums on my wishlist = Albums I want to check out sooner or later