It really is better to either have them make a first offer (or at least, give you a range) or to be slightly over-the-top when making your own first offer.
Aside from that, there are at least 3 important dimensions:
- location
- experience
- field
The important thing is that you are being paid what you think you are worth. If you are self-aware and experienced, that should come more from your own views than based on what other people are making (don't count your neighbour's money).
If you aren't sure, you need to talk to people..including friends and colleagues. I mean, honestly, you say you have a hard time finding some information out, but don't feel comfortable talking to the most important people about it. Get over it and talk to them.