Im using a dust2 modified map to better my aim and smokes, but i need the noclip command to move faster for the map.
First you need to enter
sv_cheats 1 into the console, to be able to use the noclip command.
Then you can either just type "noclip" on the console or bind it to a key like so: (again in the console)
bind M noclip
pressing M will enable you to fly trough walls, pressing it again will disable the noclip function.
Not sure if you're using vanilla dust, but there are some GREAT dust_2 smoke practice maps in the workshop, look for them, they have pictures and explanations and exact spots where to stand and where to look, and they have them for most other maps too.
For aim I'd suggest getting a practice map, there are quite a few nice ones out there.