Tech skill opens up the opportunity to use mind games and it's equally important. If you cannot make yourself wavedash 100% of the time you try to do it then it's a less reliable option to juke someone with, you need to be able to wavedash, waveland, l cancel, short hop, and successfully use all of your moves when you want to such as tilts and aerials in the right directions with the spacing you meant to use.
Most people will react certain ways to certain things and different levels of skill. At a low level of skill players react predictably and use many techniques that are ineffective at higher levels of play such as random forward smashes with Marth. Something to remember that I've heard from Cactuar and have been implementing on my own is that movement > moves. It is much more important to be able to run around the stage fluidly before and after attacks, I mostly play fox now but this is true for all characters. Here is why that's so important, play that game where you hold out your hands and the others person hands are under yours and just have them sit there under your hands for 5 minutes occasionally twitching but never slapping, when they finally do slap it's going to be so unexpected you probably will not be able to react to it. The same happens in melee, you do actions that appear aggressive but with spacing that makes it so that you can't be punished for it the whole time you are really just 'twitching' under their hands making them nervous, sooner or later you rush in before they can react and keep enough pressure going to finish off the stock, then they come back from invincibility and probably kill you, assuming you play at a high level.
About tactics, they change based on skill as well, against low level people my tactics vary, either 1) I just run around wait for them to miss and just kill them, or 2 if they are slightly better and won't throw an attack for a second I just bum rush them before they expect it and if they are bad enough they won't DI properly and you can get some very easy kills. Against better players it involves a lot more poking and prodding to see how they react to things, even top pros usually have a way they like to react in certain situations, the difference is that once you find it you only get to exploit it ONE time so make it count and get the stock.
Have fun and play smart,
Binx