I think you need to be careful when you are toying with reinforcement. Positive reinforcement can be a good thing (the fun in lucid dreams is positive reinforcement in itself!) but with negative reinforcement you have to sit back, reflect, and realise that you are, essentially, "punishing" yourself and you don't want to do that; you have to like yourself and treat yourself well. I wouldn't worry too much about trying to tie in masturbation with your lucid goals. I masturbate about twelve times a day because I am in a really boring job and it doesn't affect my ability to achieve lucid dreams. At the end of the day I am ready for a good night's rest.