Similar to mohair tack, pulled wool pads should not need frequent cleaning. Only do so when your tack is very dirty. Pick out any debris that may be stuck onto the pad and then rinse it with cool water. You can also use a lint roller or a vacuum on a very light setting to remove debris before before wetting. Use a small amount of wool lite, lanolin soap, or a similar wool friendly detergent if desired, but typically this is not necessary unless your pad is VERY dirty. Only use the basic hose nozzle - do not use a power wash attachment or anything that will exert force onto your pad as this can cause unnecessary and uneven felting. NEVER put a pad in the washing machine or submerge it fully into a trough/bucket. To dry, lay flat or hang. Keep out of direct sunlight.
When riding in muddy conditions or thick brush, it is advisable to put a thin blanket over your pad to prevent stickers, thorns, pine needles, etc from attching to your pad. This is also why I do not recommend oversized pads as a pad that is mostly contained under your saddle skirt is less likely to attract debris.
Make sure your horse is clean(ish) before placing the pad on its back too, as this will prevent dirt buildup.
It is also recommended to rotate your pad every few rides especially when it is new. This will help it to wear and break in evenly.
New pads will take about 10ish rides to properly break in and begin to felt. Pulled wool saddle pads will compress down about halfway, meaning a 2" pulled wool pad is equivalent to approximately a 1" standard felt pad. A 1.5" pulled wool pad is equivalent to approximately a .75" felt pad, etc.
Ensure your saddle fits properly BEFORE buying a pulled wool pad. A common mistake is using a thick mass produced felt pad to accommodate a saddle that is too wide and then switching to a pulled wool pad of the same thickness. (I.e. switching from a 2" felt pad to a 2" pulled wool pad). Pulled wool pads are excellent for your horse's back but they are not a solution to poor saddle fit. If you have specific fit questions, you are more than welcome to send me photos.
Happy riding!