Agree 100% with lonerider... save yourself a lot of pain during the learning curve by learning to do things correctly the first time with lessons. You'll progress faster and build a proper foundation for your riding and avoid ingraining bad habits that will be harder to correct later.
Learn about layering and quality base layers, mid layers, and outerwear. Proper layers and good gear is the key to staying warm and dry while riding which makes for a happier day. Bulking up with cheap long johns, two pairs of socks, a sweater, scarf, and restrictive Columbia jacket is not the way to stay warm and dry.
Get a helmet. Seriously. It could save your life.
Read many of Snowolf's excellent posts on turn initiation, visualize the concepts even mimicking the moves on dry-land.
Read and understand the basic rules of etiquette and trail safety.
Ride trails appropriate for your ability level. You won't have fun falling every 10 feet on a black and everyone else will hate you for being there when you shouldn't be.