Get yourself a diary and keep a record of the work you do daily , keep on top of the paperwork side of things with regular invoicing you need cash flow through the business, i tend to get my customers to buy the large items though my account this keeps my turn over lower avoiding vat it doesn't take long to get to that point. Best of luck . Kop
Written clear estimates or quotes that define what you are doing with clarity so the customer knows what they are getting and importantly anything you are expecting them to get or do.
Never pick a fight with a customer in your early years over half an hour or a few small parts.
You want happy customers that pay your bills and recommend you.
And finally don't under sell yourself. Being SE include s overheads and no sick or holiday pay.
PS don't forget to save for your tax and NI. I do this every month by buying premium bonds
Regularly do job breakdowns on quotes you've done for jobs and see how much / little you've made.
Constantly check how much goes into your pocket after all the quoted expenses and other item you didn't include.
Cross refernce that with the amount of time you spent on the job to get an hourly rate.
Try and set a price structure and stick to it.
First hour, additional hours, half day and full day.
Set a price for common jobs.
It’s easy to end up working for nothing.
Certainly keep on top of the paperwork learn how to negotiate with merchants they will do deals!
Don't dismiss the idea of doing some labour only subcontracting till you build up your business.
Great advice in all the posts above ^^^^^ , I hope you are ready for it because if you think you have worked hard before .... you haven’t , believe me !!!