When I first started out offering pressure washing as an add on service was due to a few of my domestic customers asking if I did it. I soon found out most already owned a domestic type washer but it either broke or they found out it was useless on block paving driveways.
Regarding leaflet dropping I also dropped a few business cards through letter boxes local to me that their driveways needed a good clean and just left it at that. About a week later I got my first job from that and in the end ended up doing most of the patios & driveways in that street. Many have become regular customers too.
I would also like to say it is important to include your full address, landline number and web address on whatever you put through the door as ppl like to know who you are as there are plenty of travellers and cowboys about that do so say pressure washing. Also I’ve found taking plenty of before & after pics and adding them to the website with testimonials help too.
At times when the pressure washing work drops off a bit I think I could be more proactive but after saying that most of my domestic work now comes from whilst working on the job, referrals, repeat business or through my site.
Hope this helps?
Good luck!