Depends on the style. I use 8% rule of thumb, but it all depends. Most of my stuff is around 11-18%. Bit I got a few that are lower. Hop forward beers are a no go(there are a few exceptions). I stick to mostly imperial Stouts, barleywines and Belgians.
10% of the total beer you own? Once you're hooked it'll be 90-95%. Sage advice. The style part is important too because the ABV isn't necessarily the only determining factor. Sours and wilds can come in around 6-7% but are meant to cellar for years. And vice versa, high ABV brews don't always get better with age. Just do your research and you'll get the hang of it.
