1. Don't wear flip-flops to work
You're there to get a job done and earn respect. It's tough to do that when everyone is focused on your toe jam. On an unrelated note, this goes for tank-tops too.
2. Don't wait to buy a new pair
They're pretty inexpensive so make sure and buy a new pair a year or at least every other year. Remember, you wear them in the summer and sweat
like heck. They get nasty.
3. Don't ever wear socks with flip-flops
I shouldn't have to even say this, but I did see it twice last year. Mistakes like this hurt us all.