I've used every type of drysuit there is for diving and sailing and I've dived a lot in the sub-Artic/Antarctic zones. The bag suits (the ones made out of a laminated waterproof material) is what you're talking about I assume.

When you first don it, squat and open the neck seal. This lets the air out. Other that that you can "burp" it should you go in the water.

Somebody said what you wear under the suit is the most important and thats about the MOST important thing you can say about a suit besides don't pee in it.

Think ice climbing if you're going out in the winter. A layer of wicking material (polypropylene, etc.) which usually comes in three weights (light, medium and heavy) based on your activity level (this gets the sweat off your skin). Go for the medium. Then you need an insulating layer which is fleece or any of its derivatives. This is what keeps you warm. The tighter the weave the warmer the pile/fleece is ... there's the same light/medium/heavy set up.

For boating I use an Ocean Systems suit with midweight polypro and a heavy fleece layer. I've spent as long as 30 minutes in 40 degree water (I was the rescue dummy for a practice session in NJ in February) before starting to get uncomfortable.

A lot of people think their suit leaks and what it is (usually) is sweat.

Although you already have the suit... I like latex seals and full latex feet (don't forget to use the layering on your feet - I go with a polypro sock and then a heavy duty wool one).

Anyway .. you can't beat a drysuit for cold water ...

good luck

gary