Wind
Soon after I soloed, I flew in the gusty wind. As you noted, landings are the trouble spot. I would always touch base with a more experienced flier at the field before I went up to make sure he was "on call" if I had trouble getting her down safely. I also tried to time my landing during luls in the wind. I only had to hand off the tranmitter once and it made me a better flying for not letting the wind keep me grounded.