Be Prepared

Spend time polishing your performence so that it becomes second nature.

Don't try to be clever or take risks.

This may mean changing keys - altering pitch - cutting out flashy bits on an instrument.

Aim at producing a solid, competent performance that you can and the audience can enjoy and you will slowly build back to the performer you were.

Finally and most importantly - dont be hypercritical. Mistakes you know you have made are often totally missed by an audience.

Hope this helps