How does someone get better at KI?

You should get knowledge about anything about the game. Frame data, basic and advanced mechanics…
You should be able to see a match and identify what is happening, and why it happened. This category will help you:

And this guide it’s a MUST:

You should practice a lot against other people. I remark people, since the CPU is bad for training, since you will use strategies which doesn’t work on human opponents. Try to fight against people who is better than you, and who fully understands the game. You don’t have to be destroyed by a 5 stars killer, but if you play against someone who beats you consistently AND explains where your bad decisions were and how to fix them, you will start to improve
You can look for people here:

Ask, and be humble:
Nobody is perfect, and all of us are learning. Don’t be afraid about asking anything, even if looks basic. Some people are eager to help you, and even if the answer you get doesn’t show you nothing new, it can be used to consolidate your knowledge, or to help someone else.

Focus in your goal:
Put some(realistic) goals to yourself. If you are bronze, you can’t ask yourself to be the next EVO winner. Go step by step.
Are you gold? Your goal is becoming Killer
Are you killer? Your goal is being confortable with your main
Do you struggle against X character? Look for someone who can teach you the MU to improve your results

Be patient:
Fighting games are dense and hard to master. It can take years. Don’t be overhelmed if you feel you are not making progress. Be patient, and eventually you will improve. The best part is the way you walk, not the goal you achieve.

Have fun:
Over all the things, enjoy the game, because if you don’t, then you are wasting your time. If you are frustrated and can’t focus or have fun, stop for a while, and come back later. KI is a videogame, and it’s goal it’s giving you a fun time.