How can I convince my parents to let me go on a sleep over with my friends?

Don't get them mad or angry at you by being manipulative; otherwise it will be an automatic no. Plan ahead of time and don't ask at the last minute. Be nice and ask politley, but don't suck up to them. Try to avoid asking on school days and if you can have your parent meet the other parents that way your parents know who your with and that you'll be safe.