Depends on whats comfortable for you, and what level you are at. My set-up is as follows:

L + R: Auto-boost start
A: Boost accelerator
B: Shortfire booster
L: Regular drifter
R: Regular drifter
Down: Wide drift

I use L + R to get auto boosts every time, but then switch to A straight after since it doesnt have the same 10kmh top speed penalty that the auto-boost starter gives you, and it allows for a higher top speed in general. I use shortfire booster for B because I use Crazy Bear, which requires a lot of boosting to get it to 1900kmh, and thus the shorter the boosts the more I can fit into a run - if you are using machines with greater boost or speed deacceleration, or dont want your energy eaten up so much, use the longbooster instead.  There are a multitude of drifting options that I find personally useless, although other users seem to have managed to obtain good results with them.

BPA wrote:

My set-up is as follows: L + R: Auto-boost start A: Boost accelerator B: Shortfire booster L: Regular drifter R: Regular drifter Down: Wide drift

 Sorry but this set up is not possible for a few reasons

1) There is no such thing named Shortfire Booster

2) There is no such thing named Regular Drifter

3) It is not possible to set anything to Down on the D-Pad

You might want to label things corrrectly from now on because you're controlling is using things that do not exist and has something set to something it can't possibly be set to.

BPS is a liar! LIAR!

 No.

This pig character is a regular grease ball.