I like to use the London shrink method for preparing wool fabric. It's simple and much less expensive than taking a length of fabric to the dry cleaners. God knows what they actually do there, if anything, other than waving some steam around. I used this method way back on the toggle coat so there is more information in the archive.
It's really quite simple. You will need an old sheet torn into 30" wide strips. Soak the strips in a sink of water and then wring as much water as possible out of them. Lay the damp strips on one half of your wool fabric and then fold the wool over to make a "sandwich". Fold the fabric up to make a manageable package.
I then wrap the whole mess in some plastic sheeting to keep the moisture in. I let it sit over night. The moisture in the sheeting will gradually be absorbed by the wool, and in the morning it will all be of a uniform dampness. Unwrap and allow to air dry.
Before cutting your pattern the cut edge of the fabric must be squared. This will insure that you have "grain perfection" and the garment will hang well. Pull a thread across the width of the fabric. Wow, look how easily I did this! That single thread is as strong as steel. I think my bargain "wool" is mostly NOT wool. Otherwise the thread would have been breaking constantly.
I did a burn test, and although it didn't roar into flame, there's a hard plastic melted edge. Oh well, I'm not going to agonize over it. I have $30 invested. It's a great color and has a great hand. I'll just avoid gas stoves, bonfires and candles.
I cut my pattern pieces and mark the darts and placement lines with tailor tacks. I don't bother to tailor tack the buttonhole / button positions because they always fall out way before I get to that point. I think that's enough work for today. I'm actually to the point of actually putting this coat together. Yay!