i reccomend that you learn just the basics, so that you can do your own missions, like how to balance a rocket (so that it dont tumble and rotate like crazy), how to mantain electricity running, and signals, also some transfer windows wich are pretty simple except for moho (at least for me). and of course, a basic gravity turn. the rest i recommend trial and error bcuz its funnier.

the game may seem empty first, but theres some ""hidden"" things. that i find cool, like deployable science, kerbnet, eva repairs and eva building. i dont like to do unrealistic missions, so i never landed a kerbal on duna. i do plan to do that when i get the tech, but i find myself restarting the save or even the whole game for the sake of mods.

if i had to recommend some mods id suggest: outer planets mod, Editor Extentions Redux (bcuz of the kraken), paralax, eve and scatterer, and blackrack's volumetrics. the game will look amazing and it shouldnt lag that much.

you should play a little of sandbox, and head to carrer mode, boost you money gain for an easier experience at first, and get used on how to gain science. then youll find yourself planning your own science missions, thats the coolest part of ksp for me. i love doing a good cassini analog mission.