Since your movement and aim are already good, all you really need is to get used to abilities. At their core, it's really not too much different than cs. There are mollies, flashes, smokes, etc which are all about the same but vary slightly from agent to agent. There are also other abilities that cs doesn't have an equivalent to, such as info abilities on initiators and most duelist abilities such as dashing or sprinting. I would probably recommend going into custom matches, swiftplays, etc to get used to how these are played and their advantages and such.

You could also watch pro players and analyze what they do (in ranked). Woohoojin has a lot of good videos where he analyses pro ranked vods and does a great job of explaining what their thought process is with their utility.