I started diving about 20 years ago and find that the easiest entry is one that they usually don't teach in classes. Instead of back roll or giant stride, I set up my gear, put on my mask, snorkel and fins, inflate my bc and put it over the boat into the water. Then I slide into the water and sit on the tank, put my arms through the bc and it slips right on. It is so easy, unless there is a current. I hurt my back in Honduras a few years ago climbing onto the boat with a bc and integrated weights. I won't do that again. I find that most divemasters are very accomodating in Belize. Just explain to them what you want.