This is a hard achievement. First, the game resets itself every day, so you will need to learn a new way every day. If you are going for this, be sure to be max level first, as the upgrades help. I used sharp turning, battery and jump storage. Shield storage is no good: you will not get enough shields for using it, plus using shield sometimes negates your "perfect region". Not always, but sometimes it does. I don't know if it is a bug or how it is supposed to be, but be sure to get "Perfect Region" on screen after finishing it, to be sure it counted. There is only exception, as I explain later.
A "perfect" region is a region where you don't crash nor bump into any obstacles. You can notice you bumped into something by the "multiplier down" notice on the screen, besides the other obvious effects. Using a shield, as I said, sometimes also negates the perfect region, sometimes doesn't.
To finish nine regions, you are probably going to need a lot of yellow pickups, so as to keep the sun up. Be sure to collect them, especially in early regions, otherwise you will have problems. When the sun is down, it also becomes harder to see the obstacles, which ends up being an additional disadvantage. Later they get way harder to collect. Sometimes in later regions they are in really dangerous paths, so try to get through the first 4-5 regions with the sun on top of the screen, and later you can use the portal, as I explain further ahead.
There are some important "skips" you can use and still get perfect region, which are really important. For the first two regions, try to get the quick portal that teleports you to the end of region. This is a huge time saving and will help you keeping the sun up if you find a portal right at the beginning of both regions.
Besides these portals in the first regions, you can enter a portal for another dimension once. This portal is different because it has a "frame" around it. Be careful, you CAN crash on the frame. Even though it does not show "Perfect Region" when you finish this special region, if you do it without bumping it will count for the achievement, which is nice, because this other dimension is much easier and safer. And as a great and necessary bonus, you reset the sun, which goes back to its position in the game's start when you leave. The portals usually appear on the same locations, so have an eye out for them once you learned them. Since you can only enter it once, I recommend using it at least on region six, to actually use the time reset advantage. It would be better to use it on seven or eight, so you don't have to worry about collecting anything in the last regions and you get to skip a harder region. Region nine is the hardest and best to skip, but you probably won't have the chance to learn a portal location in it or last this long without resetting the sun.
Besides that, it is mostly skill and patience. For the first regions, try to find a good path on that day and keep improving from there. If you find a good path, which you can do consistently, you can simply keep improving and expanding it until you get the achievement. But this is easier said than done.