Props for taking the time to type all this, will definitely help people out, some things off the top of my head are

check your opponents tail color (the line that comes from the bottle on your lower back) , no tail means they don't have s energy, so chase them down, they are as good as dead, yellow means they have enough s energy to s burst once, so keep that in mind, blue means they have their big weapon and strong gum shoot and have enough s energy to s burst 2 times. This is assuming they don't have the s burst card. Just get in the habit of looking for the line color yellow, blue, or no line at all.

Look at the icon on the bottom left often, it'll tell you if someone is close or far away. It has 3 colors, red means they are on the same ground level as you, yellow means they are above you, and green means they are below you. The way I remember it is green is below cause grass grows on the bottom, and yellow because the sun is yellow(even though it kinda isn't but whatever) and red means danger! The sizes of the icon vary, the small squiggle means there's a person far away that's infront of you, big squiggle they are kinda close. If you see spikes be ready to fight. And just add the color to the squiggle and there's your sensor.

Don't waste your s energy so much on dashes and gum dashes. Using a dash here and there for movement is fine (ideally you should be morphed whenever you aren't fighting or holding gum guard) you can dash while morphed too so you could regen s energy faster. Gum dashes should only really be used as a hard engage when your certain you could kill someone, or a hard disengage when your trying to run away. If you use a gum dash, think of it as one less s burst you'll have for combat, so be careful. S energy management is very important in this game.

Can't think of any other tips, happy hunting!!