This is a very basic guide that will help you translate into the CS:GO competitive scene by playing with bots.

Create a Deathmatch match with bots on any map, although I recommend Inferno. Once you have done this open your console and type sv_cheats 1. If you do not have a console go to Settings > Game Settings > Enable Developer Console and set it to yes. Press this key "`" or more commonly known as the key under "ESC"/"Escape". Once you have done the first command you have an option. Depending on your PC you may or may not be able to handle this command. As I've already recommended you have a GTX 650, if you have lag in the game normally or do not get around 75- 200 FPS I recommend you stop here. For Anyone who as a GTX 650 you should be able to do this command. Now the higher you set the value the lower FPS you will get and the more unplayable this will be. Anyone who has above a GTX 650 should set the command "host_timescale" to 3 or under. Now say you have a GTX 1080 you can set this to whatever tf you want such as 10 or 15 and you should sustain well above 60 if you have a good processor. What the command does is it speeds up the entire server making it extremely hard to aim and control your character. I reccomned you start with the value of 2 on this command as you should work your way up through difficulties. I STRONGLY, VERY STRONGLY recommend playing with bots at easy difficulty as when the game is sped up this much they can shoot you very very fast.

bot_knives_only - Makes it Easier
sv_acceleration 50 - Makes it harder to control your character
i guess thats it

kill the bots... use awp ssg or pistol dont use automatic weps because that ruins the challenge

litterally easier to aim at ppl's heads when they're not moving that fast huh?