Singles vary much. When I averaged about 25-35 my singles weren't much better than my average, and suddenly when averaging about 20-21 I got a 11.68 single. Still stands as my single record when averaging 16-ish now -.-
OT:
Practice is the way to go. Go slow and think about your moves instead of speeding up, trying to beat your record, you will rarely accomplish anything that way.
Try to find out what you need to train the most. If your LL sucks, learn those algorithms and try to find out if you have some sucky algorithms to alter. If your average PLL is 3 seconds, and your Eperm is 5, you probably want to practice your alg or find a better alg for your fingertricks. If your f2l is slow, practice it. If your cross is slow, practice it. When you are good at everything, repeat step 1