If you dye wool, there's a few steps you need to do to avoid shrinkage.
I use a 5 gallon bucket or you can use a new plastic trash can. You can use hot water to dilute the dye, like a gallon of hot water, but then dump a bag of ice in, so the water is cold. Then add more cold water as needed. You must make sure the water is cold if you want to avoid any shrinkage.
Do not put the garment in dry. Soak the garment in ice cold water first, you'll get a more uniform dye job when the garment is first fully soaked in cold water.
I suggest waiting for warmer weather, so you can let the garment drip dry in the sun on a folding chair or something you don't care about getting dye on. I like to rotate the garment and hand squeeze out any ends where water "pools up", to avoid those ends being a bit different color.
After it is dry, I re-soak the garment in clean, cold water, to remove any residual dye. If you don't, the residual dye will come out the first time you're hunting in any rain. I then repeat the step of drip drying on a chair, on a nice warm day.
Some of the browns can turn out a little pinkish, if done on already tan/brown wool. I've had great luck turning wool into a rusty brown color, by mixing in Rit Tangerine and Cocoa Brown.
I also suggest rubber gloves when putting hands in the water. For karma, I use an aluminum arrow to move the garment around in the dye water.
Here's a couple really good recipes for colors. Keep in mind, the pre-dye color of the garment will dictate a lot of what you can do.
http://www.steinlaufandstoller.com/fabric%20dye%20custom%20colors.htm http://www.ritdye.com/frequently-asked-questions#colors