Dude...you're only level 15 lol. Relax, most of the do's and do not's will coke naturally or your party will most likely set you straight. I'll type up a few of the big guidelines though, just in case nobody tells you as you go about your journey.

1. Make sure your Tank stance is always on (unless there's a second, more experienced Tank in your party)

2. In mobs, overpower will be your best friend. Use this fairly often to hold aggro. Do not lose aggro under any circumstance.

3. Use your defensive skills (some people may refer to them as "cooldowns" or "CDs") often.

4. Always face enemies away from your party.