How to airstrafe

1. Firstly you want to be moving faster than 16.5hu/s (you can turn on the speedometer in the HUD settings)
2. Make sure you're looking exactly in the direction you're moving in (technically you don't have to but this is the easiest way)
3. Hold A or D to turn left or right, and then turn your mouse slowly in that direction (any other direction will cause you to slow down). You should notice your speed increasing steadily as you turn the mouse
4. Practice this for a bit until you get a feel for it, and know what the maximum turnrate is!

How to bhop

By default the bhops have to be buffered before every jump. This means that you have to release the jump button and then press it again for every jump