If you're serious - speculate to accumulate.
Get a website, get a website, get a website.
Get a sign written van.
Get the kit you need.
Have the website at the highest point on the van, make it larger than the business name.
Get on Facebook, blog & learn to use key words that'll keep you high on the rankings.
Everyone says I'm getting this pressure washer and this piece of kit, how do I.
To build a business it's more important to have web presence than any other part.
Until you get into proper commercial, have an established presence locally you will only pick up the odd job here and there, not enough to feed you.
Farmers are tight and a lot of them will have their own kit, don't rely on this market.
I live rural, have an established business doing pressure washing only, all year round, have and had all of the above - never had a call from a farmer but my website is completely geared to businesses only and the clients I have I have had for many years.
I tidied up a storefront yesterday that a company calling themselves pressure washers had done a half a*se job on.
This looks like an easy business that anyone can jump into, it just isn't that easy and most of the residential work dries up around September, unless you know what you are doing.
Solid advice above - I always say the same, build a window cleaning round, guaranteed income every month and if you still want to get into pressure washing go from there.
Any market is a potential and you may find a magic formula wherever you go.
Good luck.