Know the basic rules of climbing. If you need to break them, at least know you are taking a risk on two lives. 1)Communicate well with your partner 2)Look out for and double check your partner 3)Never trust your lives to one piece of gear 3)Always wear a helmet, especially while belaying 4)Test new systems before committing to them 5)Knot rappels if there is any shadow of a doubt 6)Never build your anchor off the bottom of a rap chain (this is just rude)