One of the most critical, yet neglected, parts of a successful weight training program is your warm up routine. A lot of guys will either skip the warm up altogether or just skim through a half assed warm up and then jump right into their heavy lifting.
Now while they may get away with this for a little while, it's eventually going to catch up to them are they are going to get injured. And depending on the injury it could set them back several weeks or even several months in their workouts.