As your home ages, you may notice exposed wood start to decay.
Step One: Prepare Surface
The first thing you want to do is prepare a good surface to put your patching compound on. Often times, for minor rot you don't have to do anything.
In the above image you can see I drove a screw into the wood to close that gap.
If you have soft rot (you can push a screw driver through it) the affected areas need to be removed.
You also want to prepare the surface by brushing on an exterior wood stabilizing primer.
Step Two: Apply Patching Compound