These are just things that I have found when learning to dive (in no particular order)
1. don't trust your initial weighting. If your instructor did not do a proper weight check during your OW, do one now. I left OW 10lb overweighted, it made a huge difference to eventually get rid of all that weight
2. don't worry about your SAC, most likely it will drop (mine more than halved in my first six months of diving)
3. don't buy your gear until you've had a chance to try out various styles to see what you like. Don't trust anyone who tells you there is only one piece of gear suitable, work out what you like for yourself
4. don't necessarily trust your LDS, no matter how nice they seem at the start. Make sure to cross check prices of the gear they sell and try to do classes with different instructors. You'll get more than one perspective on things.
5. don't be afraid to ask more experienced divers to dive with you, most won't mind. And don't be afraid to ask them to borrow gear so you can check out different things before you buy. The worst they can say is no, and most of the time they will say yes.
6. don't ever worry about calling a dive. Every diver should feel comfortable to call a dive at any point for whatever reason. Don't worry about cutting someone's dive short or whatever, these things happen.
7. don't ever put your safety in someone else's hands, such as a DM or buddy. You are entirely responsible for your own safety and you should never become complacent. See this thread:
http://www.scubaboard.com/forums/ne...ering-diving/283566-who-responsible-what.html It is an important read for new divers in my opinion.
8. don't rush things, be it underwater or training wise or pushing your limits. When diving, take it slow, you'll see more and your gas will last longer. Don't rush into advanced classes or diving early on (like starting your DM at 20 dives or whatever), get the basics right first.
9. don't just sign up to classes such as AOW, or Master Diver or whatever. Most PADI-style specialties are quite bare of information and generally unnecessary. You'll often learn more diving unsupervised with a buddy or with a mentor. Just dive as often as you can and it always helps if you are enthusiastic about local diving.
10. don't worry about stupid questions. Yes, some questions are stupid (despite what people say
) but that doesn't mean you should keep them to yourself. Everyone has stupid questions at some time or another so ask away on forums, buddies, instructors, etc.
Anyway, there's a lot more I am sure, but those are the big things for me and it is all just my opinion so take it with a grain of salt if you want
