Mario Kart Wii - how do you get 3 stars? (part 1)

Update: Part 2, Part 3, Part 4

I've spent quite a lot of time playing Mario Kart over its many incarnations (from the Super Nintendo "Super Mario Kart" up to "Mario Kart DS"), and have been playing Mario Kart Wii for the past few months.
It took me a while, but I now have every character and kart unlocked, and the one remaining item is to get a 3 star rating on every Grand Prix. When you have a 3 star rating and play online, it shows up next to your name, so everyone can be in awe of you!

I've had a look around on the internet, and while there seem to be plenty of pages pointing out that you need to get 3 stars on every GP to get that ranking, there's very little information about how to actually do it. So, I'm hoping to put up a number of blog posts which will give you tips on how to go about it.

Marv's First Tip: practise.
As with many other games, you will get better and better as time goes on and you have played the same level over and over again.
If you have played through enough to win a gold cup in every Grand Prix, the chances are that you'll have a few one-star ratings (and perhaps the occasional two or three-star!). Now you need to build on those skills and keep playing the same tracks until you are fast enough to win every time. Make sure you are taking advantage of every shortcut (where appropriate - if it's off-road for too long, it might not be worth it) and using mini turbos at every opportunity. Use a lot of tricks, but only where you don't have to go too far out of your way to do them, or where you end up in the air for a long time unneccessarily.

Marv's Second Tip: choose a character and vehicle and stick with it
Find a character and kart (or bike) combination you like and stick with it for a while. The characters and karts are all different and mostly have advantages and disadvantages, but if you keep switching you may find it difficult to pull of that tricky-shortcut because you aren't used to the handling.

Marv's Third Tip: bikes are better
Bikes are probably going to make it easier to get 3 stars, because even though they are generally lighter and more easily knocked around, they can get a speed boost on dead straights, which karts cannot. My own character/kart combination is my Mii (medium-weight - roughly the ame as Mario) and the Mach Bike. This gives me a fairly low top speed, but it's pretty good off-road, and the acceleration is nice. It also has a good turning circle.
Ideally, acceleration shouldn't be an issue, but when you are playing a GP, as opposed to a Time Trial, you know that you will occasionally be hit by blue shells, red shells, Pow blocks, lightnings and so on - no matter how far ahead you get!

Marv's Fourth tip: turbo after spin out
This is of use mainly to those whose characters have low acceleration ratings. When you are spun out, or hit something and stop completely, you can get a turbo start. Hold the brake (/powerslide) button at the same time as the accelerator for a couple of seconds until you see the blue sparks; now let go of the brake and you'll turbo off at full speed!
If your vehicle has good acceleration anyway, you won't need to do this, and the one-or-two second delay will actually slow you down more (especially if you get spun out again while you are waiting). I find that with my combination (above), I do use it, but only occasionally.

More tips to follow soon...