I wish I had $15k to start with! I started with a Ryobi pressure washer and a friend I went to high school with's dad still liked me enough to give me my first job. I was knocking on doors and hanging door hangers until I found HomeAdvisor and Facebook swap & shops. That's serious as a heart attack. To this day I still rent the largest machines that I need. I don't have space nor do I have the desire to drop tens of thousands on things I can rent for a few hundred dollars and price it in.
Today I bought hoses that cost more than that Ryobi pressure washer and it felt like a milestone. Ha!
If I had $18,000 to start with, knowing what I know in two short years.. I would've reduced my expenses, put it in the bank, went to work for one of the two largest pressure washing companies in my area, worked as often and as many different projects that I could volunteer for 6 months, then I would spend $9000 on marketing and a website with the best SEO person I could find locally, I'd do projects for next to nothing in exchange for reviews on Google, and park the other $9k in the bank until after I evaluated which marketing methods worked the best. Then I'd spend the rest of the money on those and keep on renting machines and trailers.
Renting and leasing machines and equipment is better for tax purposes than buying them outright. At least that's what my CPA keeps telling me.