When you first start meditating, you could feel sleepy while your practicing. This is just because you're giving your mind a break that you don't normally give it. You're allowing it to pause from thinking for a moment. It's perfectly natural, and it doesn't mean meditation isn't for you or that you're doing it wrong. Commit to your techniques when you sit down, and if you doze off, that's okay. Make sure you've set a timer though, so you don't sleep longer than you want. There are some things that can help you stay awake! I learned some of these from Headspace and some from my own personal experience.
Make sure you're meditating in a cool environment. I don't mean a dope area, I mean a cold space. Whether it's turning down the thermostat or opening a window, staying cool tells the body it's time to stay awake. You could also turn on the lights! Not harsh ones, but just enough so your mind knows it's daytime. If your goal is to fall asleep in your bed at night while meditating, meditate at night. Otherwise, meditating first thing in the morning is a great way to wake up your body and start the day off in a good mood! Lastly, refrain from meditating after you eat or exercise. Your body is ready to rest and recover after those activities. With that in mind though, meditating while you're starving is antoher distraction ya just don't need.