Simple rule:

Don't make personal threats or to the family,

Don't use foul language,

May not like the guy but show respect. "Rep. Bohner said the following '..."

Stay to the point and be concise. You can be nice and still be very firm in what you say.

And do send it to your representative.

Nothing to be afraid of. Heck I'm speaking in front of the city council tonight with community TV pointing and video-recording me. The other day, I spoke in font of rather hostile residents about 200 of them maybe more... I'm still here and happy.

A happy cat,
Smilingcat