Be punctual! No matter what. If other people can make it on time, why can't you. Professionalism comes with punctuality. Be considerate of others. Being punctual means showing respect to others. Being punctual also shows you have self-discipline and organizational ability. Really, it's all about good planning.
No excuses unless your dog is dying and you run of of gas or stuck in the traffic and all sorts of "not so valid" reasons. --according to my dad.
In business, there are ups and downs just like in a relationship. Just do your best and never give up. Downtimes are only struggle that will strengthen your capacity and integrity, so be strong, be determined, be wise, and be competitive always to succeed.