My recommendation is this: If you are the kind of person who tends to not want to speak up, or are shy, or don't want to look dumb, or tend to rely on others, or tend to assume that nothing bad is going to happen to you, then you'll need to rethink that behaviour. I'm also new to diving, and the one thing that I've noticed in my limited experience and from what I've read about diving accidents is that you need to be bold, assertive, and uncompromising about your own safety. Speak up if something doesn't seem right. Loudly. Don't assume someone is watching out for you. Don't assume that if nobody else does buddy checks, then you shouldn't bother. Don't let people convince you into doing something that isn't right for you. If you don't feel right about the dive, or don't feel well that day, then DON'T DIVE !!! You can always come back another day, or just enjoy the beach (or where ever you are). I've gotten into the habit of occasionally planning a dive/fun day at the beach, where if the diving isn't great I have a backup plan (surfing or boogieboarding or snorkeling or whatever). That way I feel more comfortable with putting the dive into perspective, that it's not the end of the world to call a dive if something's not right.
What seems like a small issue, such as minor equipment problems, can rapidly spiral out of control. Check your equipment and your buddy's equipment thoroughly. Don't gloss over safety checks. DO THEM !!! And don't just dive with a buddy, PLAN your dive with your buddy, communicate everything, make sure that you both know what you're doing, that you're staying together no matter what, at what pressure you're ascending, etc. Make a list of pre-dive checks and put it in your BC pocket.
Start thinking of "what would I do in this situation", for each part of the dive. Problem on the surface? Breathe with regulator, make sure BC is inflated, drop weights if necessary. Get into a safety state of mind.
The rest of the stuff you can learn in class.
