Keep an eye on all four ghosts are; you should be watching them more than Pac-Man.
Learn how many flashes they will flash and count each time they flash when blue, making sure you know exactly when they'll turn back. Even if you don't need to count, just keep doing it so that you get in the habit of counting every time.
Abuse the warp tunnels, even if you're not in danger. You can still use it to get to the other side. It also helps get the ghosts near or away from you. Use them a lot, not just for escaping. Don't run in if a ghost is waiting on the other end, of course!
Know your fruits. Earlier fruits aren't worth the effort if you'll put your Pac-Man in danger.
Find a good starting route to make a way that you know you can clear a bunch of dots without getting hit, and be in safety. Good starting routes also include picking up a fruit. There have been routes developed that can get you through the whole maze without getting hit, but they don't always include eating all four ghosts, and they are difficult to memorize, and also ruin the excitement of the game.
Study the ghosts' movements and learn how to dodge them. Beginners make a lot of errors because they'll turn away from ghosts that are most likely not chasing them or not going to chase them. This wastes time and makes Pac-Man run around, not clearing the desired dots.
Try clearing each quadrant fully, and then move on to the next. Don't eat your second power pellet before all the dots in the quadrant of the first have been eaten (or unless you are forced).
Try to be near the fruits when they appear, especially in a way that no ghosts will be after the fruit, too!
After round 10, focus more on survival than trying to eat many ghosts. You'll be getting good fruit by now, so try to eat all the fruits and stay alive.
Never panic! Ghosts can suddenly run away, so try to stay alive even ife trapped. Wiggling the joystick/controls could cause Inky to turn away, and Clyde might randomly run away. Sometimes the game glitches and you even move right through the ghosts! This tends to happen the most in the areas that start with no dots, especially where the fruit is. However, don't rely on the game to glitch as it never happens when you actually want it to.