Learning to love competition nerves

Step 1: Understand why you feel 'nerves'.

Most physical symptoms of 'nerves' are the result of physiological adaptations to stress Your body learned this stuff to help you survive. If it hadn't worked, your ancestors would be something's lunch. So it has a positive use.
The 'physiological adapation' prepares you to fight or run better. Immediate stress - competition, apprehension, near physical danger - starts your adrenalin running; your pulse goes up, body temperature increases, and your capacity for extreme effort increases. However wobbly you feel, you COULD run faster or fight harder - as long as you don't hang around worrying about it. But it's your call; run - or fight?
Step 2: Use the knowledge.
Learn to shoot with it

Simply accepting that 'nerves' are a normal response to pressure and not cowardice is a powerful aid to arousal control. Also, knowing that it will and should happen if it matters is your cue to prepare for it; start looking for some competition so you're used to it and can get your coping strategies worked out.

Ride the rush Here's a different approach. If your ideal arousal state is on the high side, anxiety symptoms are just a head start on a combined physical and mental warm-up routine. Swing into it!
Use self-talk

Reminders like "Body's coming up on stream" can reinforce the normality of 'nerves'.
Phrases like "'Nerves' spell more power when I'm up against it", or "I work hard on adrenaline" can add force to your shooting. And you can surely make the second one true.

 
When it works

'Riding' anxiety is an active response; it will tend to suit extroverts.

If you work better 'pumped up', you can afford to welcome 'nerves'. They just tell you your body's responding properly to pressure.

If the symptoms are chiefly physical ('somatic'), physical warm-up and activity can turn 'nerves' into energy.

 
When it doesn't

If your ideal arousal level is low, go for anxiety reduction rather than 'riding' it for energy.

If the symptoms are chiefly mental/emotional ('cognitive') use calming techniques and concentration skills to stay focussed.