Day 1 - Bounce to get achievement. Buy acceleration.
Day 2 - Bounce to get enough distance to buy glider.
Day 3 - Stall your flight for as long as possible. Buy the first 2 ramp heights and one air resistance.
Day 4 - Hold back the left arrow as soon as you lift off to get the altitude award. Buy an acceleration and an air resistance.
Day 5 - Fly the 10' ramp. Go for distance, not altitude. Buy another 2 ramp heights.
Day 6 - Pull up as soon as you lift off. You should level off at ~20 feet, but this is enough to get both the time and altitude awards. Buy the first rocket and 2 rocket fuels.
Day 7 - Go back to the 5' ramp and get the 2 remaining awards (distance and time). Buy the 4th acceleration.
The main thing is to always go for achievements when you can. Always go to the newer ramps as soon as you unlock them, buy stuff and go back to previous ramps and get all the achievements left. Gliders are the most important, next comes the rocket, then acceleration.
 "Music Catch 2"){kind=icon}
 "UPGRADE COMPLETE!"){kind=icon}
 "Learn to Fly"){kind=icon}