That's good advice from Rybo, there.
Since I use a climber almost all the time......I also have my pick of trees, usually (because of where I live). I "try" to pick a tree with another tree VERY close....to shield me if that deer walks between me and that tree. It's as important if you're hunting out of a lock on. It's just additional "cover".
I have had bucks bust me while letting down though. I draw and then they always seem to stop in the wrong spot and stay there for 5 minutes. I hold as long as I can and then have to let down. That really sucks.
I had this happen, last year, too. I'm happy to say it was a buck I'm glad I didn't get an opportunity on, though (ultimately).