A good push will get you to where you want to go more effectively, and also help avoid extra fatigue. It's best to push with your back foot, as pushing with your front foot is much harder to balance and less common (AKA Mongo; some people might make fun of you for pushing that way).
Pivot your front foot so it's facing the direction you're heading, and take the back foot off the board, placing it parallel to your front foot and facing the same direction. With one smooth push, then place your back foot back on the board, and pivot your front foot back to your original stance placement. You could also make a few consecutive pushes before putting your back foot back on to the board, just make sure you have good balance when pushing more times.
Watch out for kicking your back wheels when you're pushing, as it's easy to get your foot caught on them and might make you lose your balance. Boards with cutouts can make it easier to catch the wheels, so make sure to practice pushing slowly at first before staring to push too fast and hard.
Now that you know how to get moving, it's also important to know how to stop. There are a handful of ways, but Foot Braking is generally easiest to learn at the beginning. It's best to start practicing this technique with the board moving slowly, and then you can try with a little more speed after you're more comfortable.
Very similar to pushing, pivot your front foot before taking your back foot off the board. Instead of pushing with your back foot, gently place it next to your board flat on the ground, and let the friction slow you down. Start with a little pressure at first, and apply more pressure to make quicker stops, always making sure you have good balance while practicing this technique.