I too am at the point of full injury (RSI) for my drafting mouse hand. First off look to getting an ergonomic assessment done for your workstation. If you cannot get one done due to non-availability here's a few tips.
When dealing with mice use always have only your elbow supported. The soft tissue in your wrist can be damaged by resting your hand on a pad. When typing never rest your wrists on anything, same problem as the mouse.
Make certain your chair supports not only your back but the position of your bum and elbows. For the underside of your lap (that bum I mentioned) you should have no more than two to three fingers between the underside of you knee to the front of the seat while still having your backside completely supported. Your knees, hips and elbows should be at right angles!!
Evoulent I understand is a good product, I went further and purchased the E-Quill mouse. Basically the vertical mouse with a rest for the wrist, it's not against the soft tissue of the wrist, so it was good. Unfortunately these mice may not, in the case of the E-Quill a certainty, are not made for AutoCAD drafting. Meaning they will not last. I do a lot of shore line digitization so my mouse click use sounds like I'm using castinets (flaminco dancers).
Braces are great in that unless the problem is addressed, then they just push your injury/pain further up your arm. Every hour walk away from your computer. Do some filing or whatever, you need to rest your arms and eyes.
Stretch!!!! A good one for the wrist is: arm extended forward, palm up. now with the other hand pull the fingers down slowly (this is best done when you have warmed up muscles). for the shoulders: try and touch the inside of your elbow (crook of arm) to the opposite shoulder, you will need to use your other hand to pull it in; another - with your right hand touch your spine with an open palm at the top your back, with the left hand grab your right elbow and pull it towards your left side.
Always go in there knowing what you need, not what you want. A lot of companies and Government offices have access to nursing staff who can do assessments. From a manager's point of view the less injuries you have the less time you'll be off on compensation or sick leave.
Always, always, always do business with a company that allows you to test-hop their products. You don't want to fork out a few $100-$1000+ on something you'll eventually rest your feet on, unless of course it was a foot rest you purchased.