All good advice on here.
My tuppence worth.
1. Be consistent.
2. Stick to your pricing. Don't go low just to get the work in, you will regret it.
3. Always remember the customers point of view is the most important if you want to keep them.
4. Be prepared for alot of hard slog to start with, if you manage to turn over an actual £15k of revenue throughput in your 1st year, then you are doing really well (Don't get this confused with customer signups, as that's a different figure, aim for £25k of new customers and that will translate to around 15-20k of actual revenue throughout in your 1st year.)
5. Keep the new business activity going, expect to loose upto 20 percent of your new signups in 5 years due to various consequences.
6. Try to run your business on the 3rd rule. 3rd away for tax; 3rd away for business expenses and marketing/growth, and the 3rd goes to you as actual wages you can use to live day to day.
7. Understand that people will take thier time to pay you. At any one time expect to have at least half of the money owed to you that will come in over the next few weeks, you can mitigate this by going to go cardless, to take DD, and get a card payment machine.
8. Dont waste your money on "thermopure" or anything else with flashy neons and slogans.
9. Do spend your money on a decent pole and hoses. Gardiners are the industry leaders.
10. Be patient.