I frequently experience sleep paralysis, need tips on achieving OBE's

For the past 15 years or so I have experienced fairly regular instances of sleep paralysis. At first they were frightening, then they became interesting, and then I had my first OBE, which was amazing. It was involuntary, however. Usually I slip into the SP state when entering sleep but last night it happened upon waking. I tried to take control of it with the goal of projecting out of my body. I did get the feeling of projecting rapidly skyward, which is what happened the two other times I have had uncontrolled OBE's. For some reason though, I couldn't bring myself to open my eyes which is not usually a problem. But now that I think about it, if I'm projecting out of my body, why should I even need to open my eyes? Just wondering if anyone has any suggestions on what I need to do in order to project voluntarily when I find myself in a state of SP, and once it happens, how can I control it and enjoy it to its fullest?