1) In general I have found (Note: my "data" is purely my experience doing this in the USA.) that insurance agents are good with giving money but lawyers aren't.
2) Know what you are asking for. See below:
If it is the local pizza shop, are you asking for money or food for the team?
How much money do you want? (Better to be low enough they will have it on hand, but not too low or you don't look professional.)
Do you want money or giftcards?
I hope that helps!