Short hop fair toward your opponent and then DI back away from them mid-jump is handy. It'll land the third kick but if they try to shield grab, you'll be out of reach. A good KO move is bair, so a running forward turn around bair. Up tilt to get them in the air for combos. A good edge guard technique is stringing fairs together and then a hammer (depends on character and stage). Kirby's short hop fast fall by itself is good for maneuvering around the stage, and is good for mind games. Kirby is also a character that can utilize fox trotting. Kirbycides can be great if you are one stock up and you are at high damage. Just do it and you'll have a stock + a stock's worth of damage between you and your opponent if you haven't already won the match with the Kirbycide. Best way to do this is when they aren't expecting it and off the stage while you are edge guarding. Just practice using it against opponents and find the best way. Find out which copy abilities work for you. There are some characters where it's better to have your inhale ability for Kirbyciding, star KO's, or racking up damage with inhale + spitting. Just learn how to properly space yourself against different characters and play styles. Down throw + up tilt can do some damage, especially at 0%. Some people don't DI away from it and you can either chain that for a bit (works best against heavier characters), or you can do more than one up tilt, just find out what you can do. Again, read the FAQ, the hammer can be deadly, especially in the air. Against some characters at certain percentages you can do dair to forward smash after you land. It usually puts them just in reach and they can't do much to stop it. Good KO move. Not sure how full-proof that is, I'm certainly not the authority on playing Kirby--though I too hope to be one day.
To do the running forward dair: "Pivot Break
-While doing a dash, start to turn around, and then immediately jump, and flick the control stick back in your original direction. You'll be turned around, and can do a back air or whatever while still maintaining your initial direction and speed." -Omnigamer
There is a priority thing in the FAQ.