Visitor Visa for Client Work

[ag7738]

Hi
I am applying for a visitor visa to visit a client every now and then for meetings/advisory work.
Can you tell me what could be a good description of business activities, if I need to attach a letter of support and invitation from client and what would that entail? Also my travel dates would be decided every now and then as the project goes on, what should I be writing in itinerary?

I just need a rough idea about these, as I have never applied for visa on my own.

Thanks
AG