When you're playing soccer, the last thing you want to worry about is adjusting your shin guards every five seconds. Shin guard sleeves work better than traditional hook-and-loop straps for keeping the guards up. If you don't want to spend money for a new pair of sleeves, you can make your own by raiding a closet.
Lay one leg of the hose/tights over one shin guard. The narrowest part of the ankle should be right at the bottom of the shin guard.
Cut the hose/tights about 3 inches above the top of the shin guard (if necessary, cut the foot off at the narrowest part of the ankle).
Trim the sleeves until they're at a length you like.
Repeat steps 1-3 for other shin guard.
Test-fit the sleeve. Either hold shin guard against leg and slide sleeve over, or slide sleeve over leg first, then slip in shin guard.
Adjust shin guard until it is at desired location.
Slip soccer sock over shin guard and sleeve.