Most racers like to fly with more front-foot pressure, which equates to more power and more upwind drive.
Out of the box, start with the -2° spacer.
Add tail wing angle in 0.5° increments to add the amount of front-foot pressure you like most. The windier it is, the more you'll need to reduce tail wing angle to reduce power. The lighter the wind, the more you'll tend to add tail wing angle to boost power.