A very important thing. I use my spare time for volunteering at Code Clubs and STEM events. If you are asking me to do something that requires me to use my time, please bear in mind that we all have to eat and keep a roof over our heads.
Please contact me by email with a rough outline of what you require.
For Documentation/Tutorials for your product:
Please contact me by email with expectations, a rough timescale, and a description of the product. you *will* need to loan me the product!
For speaking engagements:
I will not travel to your event unless you can provide travel expenses. The fee for speaking depends largely on the event and structure.