I tried to edit my post, but it's too late. Sorry for the double post.
But THE MOST useful thing I brought to basic was electrician's tape of all things. Generously tape your heals with this stuff during ruck sack marches and it will help with blisters. Your socks slide against the smooth tape instead of rubbing your heals.
It was wonderful. Also good when you first get your boots and have to break them in.
Baby wipes are good too.