Honest opinion:
No one cares. All they want is for you to clean their windows, this is a trivial matter to most people.
The last thing they want is a welcome pack that’ll go straight in the bin.
All they need it your email/phone/website info.
Think about it, if you weren’t a window cleaner, but had a window cleaner yourself, would you care about a welcome pack? 90% of people would say no.
Customers don’t care how the method works, what pure water does, how’s it all done etc etc. They just want clean windows.
There are some window cleaners who love to over complicate everything. In doing this, they just create a cringing mess.
It’s basically a waste of time and paper 📝
😎
As for add ons - just tell them your services, or have the add ons written on your ‘windows cleaned today’ leaflets.