Picking your deck size can be super confusing. Most of the time skaters look at shoes size for board size but this only comes into play if you either have a small foot or are a grom. Picking a size is a preference thing and changes depending on what tricks you aim to do or locations you skate. If you're just starting out, a size 8.0 or 8.25 is a good size to start learning tricks as there is more room to land back on the board. If you are doing stairs, 8.25 + is better for stability on landings. If "flip tricks" are what you're after than 7.5 - 8.0 skateboard decks will make it easier to rotate. Try different sizes but generally when you fin what you're comfortable with than you normally stay on that size.