Here's a few pointers on how to get the most out of critique you receive:
1) Analyze whether you agree, disagree or even understand the critique. See how it relates to the work or your approach and development in general.
2) Consider or verify the source of the critique...particularly if you do not agree with it or it seems confusing. If their work is pretty decent then pay attention, if not then disregard if you don't agree. But always be considerate, polite and thank them. Conflicting critique or advice should definitely be checked out. Some people know what they're talking about, others don't...simply check to see who is who.
3) Ask for clarification if you don't quite understand a point, but try to be specific, and ask only after you've done some research and checked any references offered. Try to study and understand the points of the critique on your own first.
4) Follow through...do your best to follow through on the critique you feel is most valid. If someone says you should work with simple forms and shapes to understand value better, by gosh, do some drawings along those lines and post them up. Don't just keep banging away at your "vampire knight mounted on a flying armored dragon"...or, you know, whatever. It is very frustrating to offer sound, carefully considered critique to someone who simply ignores it. Basically it means you will no longer receive valuable critique from that individual.
5) Don't make excuses...excuses mean you are not ready for critique and the effort required to improve.
6) If someone recommends a book or resource, get it. It is recommended because it will help you with your development. If this is not an option, you aren't ready for critique.
7) Don't ask for "tips, tricks or techniques". There aren't any. At least there aren't any someone else can tell you and have you understand. Tips, tricks and techniques are what you develop on your own and they contribute to your own style and expression. They are too subtle, individual and tied to the media and hand skills to be able to communicate easily.
8) In general, if you are not willing or ready to follow advice and critique, don't bother asking.
9) Be aware that what may at first seem like harsh critique is still intended to help, or shake you up, or break through all the BS you may have heard. Accept it in the spirit intended.
10) Keep working hard! But work effectively...
We now resume your regularly scheduled forum...