The game is available through Flashpoint.

Holding the down key very quickly drops you to the ground and also lets you accelerate down slopes. If you aren't on a slope while crouching, you quickly lose speed, so you usually want to jump before the ground levels out.

Jumping while tilted forward can boost your speed because the jump propels you in the direction the top of the skateboard is facing. I call this bhopping and you can build incredible speed if you chain multiple jumps together.

Dropping down onto slopes converts some of your vertical speed into horizontal speed and is the best way to quickly accelerate.

You can buffer jumps by holding up.

If you wipe out and your body reaches the finish, it still counts for a completion of the course.

Sometimes when you move at high speeds or rapidly change direction, your body can briefly get displaced and needs to settle somewhat before it returns to normal. Usually your body lowers and turns horizontally which messes with your physics. Pressing the down key can help reset it.

I don't really understand springs, sometimes they give you a ton of speed and other times completely stuff you. Something I've noticed is that coming at the first spring in C6 from below sometimes gives you a big forward boost.

Be careful not to move too early when you click on a level. It seems to mess with the in-game timer and usually results in you going straight to a game over screen. Here is a weird example where I didn't immediately lose, you can see the timer only has 10 seconds:

There is a glitch when you click a level then click a different one as it's fading in: you play the first level but the progression counts for the second. You can use this in fresh-file Any% runs to play one level repeatedly and still progress the game. Found by Gaminator3333.