Determine just how far you want to take your project. Maybe your saddle only requires a good cleaning. Maybe it requires a full cleaning or restoration, this means pulling parts off to clean behind them. Based on your saddles cleaning requirements not all the following steps are necessary.
For a deep cleaning or restoration plan on this taking a significant amount of time. If you do not have leather tools or some leather working knowledge, I am not sure I would attempt a restoration. I can almost guarantee you will find something that has to be repaired or replaced depending on the age of the saddle. It's possible to even break something while taking it apart. There are surprises around every corner in a restoration.
Please read everything carefully. These instructions are to help you only. I have seen very old saddles crumble when the cleaning process is started. Proceed with caution or go to a professional if you are unsure.