1. Make sure to start paddling (Up arrow key) right after the race starts. Note that starting the race "eats" your input, so if you press Up while Tux is walking toward the line, he will not paddle until you release Up and press it again. I solve this by pressing Enter to start the race, then immediately pressing Up

2. Zigzagging helps you accelerate faster, especially at the start. It's a rhythm to learn, but it can easily save 2 seconds. Just press Left-Right-Left-Right-Left-Right and so on, try to do it in such a way that you keep going in the same overall direction. The top records on Frozen Lakes Any% No Game Lag ( https://www.speedrun.com/extreme_tux_racer/Frozen_Lakes#Any_No_Game_Lag ) show very effective zigzagging at the start. Notice how they reach 60 km/h in 4.x or 5.x seconds. Without zigzagging, it takes well over 7 seconds to reach 60 km/h

3. Make sure to stop paddling once you reach 60 km/h. Above that speed, paddling only slows you down

4. Building and preserving speed is generally more important than tight lines, because acceleration is very slow. You accelerate much faster on ice, so try to hit ice patches if they're not too hard to include in your route. Avoid or mitigate route parts that lose a lot of speed

5. Pressing the Up arrow key while airborne will make Tux flap, which makes you fall down a bit slower and allows you a tiny bit of air steering with Left and Right. If your keyboard allows it, you can gain sharper air steering by pressing Up + Down + (Left or Right)

Update 2021-12-07:

• Updated the link to examples of zigzagging
• Added a sentence about sharper air steering
• Removed the sentence about the guide probably needing updates in the future :)