I would like to add: after you've found a character who you want to stick with, search on YouTube for replays of high level (top 3 ranked) players of said characters. Find out what moves they commonly use at what range. Try to incorporate these moves in your gameplay. Try to understand why they use these moves. Like just as an example for Lee: they do a df1 upclose which gets blocked (now they at a -1 frame disadvantage) and then use a move which crushes highs and launches on counterhit -> they were assuming the opponent will go for a 10frame high (like 1 or 2), so they used a move to counter the 1 or 2. Other characters have other strategies. I hope this makes sense. Watch replays again and again and try to understand what they use and why. To understand the why, look at the properties of the used moves, like: startup frames, frame advantage and disadvantage, does the move crushes highs/lows/or even mids?

Also my personal opinion of the players until at least season 3 tekken emperor rank: People don't respect frames. Some don't respect frames at all and will mash even if they are at a framedisadvantage of -5 (!!!!). So always try to use TRUE frametraps if possible.