First and foremost, don't ride alone!

Secondly, get a helmet, some gloves, a mini-tool, some tube patches, a mini-pump and learn some basic repair techniques. This could save you a long walk back to the trailhead.

Keep your elbows and knees flexed. Don't ever lock out these joints. Use them as additional suspension.

Don't look where you don't want to go, you WILL go there. Instead, focus on the best "line" and concentrate on it. You will find that by focusing your eyes where you want to go, your body (and bike) will follow.

Going too slow will cause you to fall over more. Sometimes more speed is what is needed. Not having enough forward momentum causes you to steer eratically, and flop from side to side.

Learn how to use your body weight to make the bike do different things. When climbing, stay seated toward the tip of the saddle, bend at the waist, drop your shoulders, tuck your elbows and pull down on the bars.

When descending, get your butt off the saddle and slightly behind it. The steeper the incline, the further back off the saddle.

That's all for now!