How we change what others think, feel, believe and do
If you want to persuade somebody to do something, first ask them to do it and then, before they have time to respond, thank them for doing it.
Hi, can you close the door? Thanks -- that's very kind of you.
Could you lend me fifty? Thanks, I know it's awkward but I know you're a great friend and I'll pay you back tomorrow.
A thanks is an act of closure, sending a signal for the completion of an agreement. An effusive thanks (but not over-done) can help cement the closure. This makes it difficult for the other person to 're-open' the case and contradict this.
Do be careful when doing this -- if you ask for more than the relationship will bear then the relationship will suffer as a result, even if the person complies with the request.
It can be useful sometimes to include an apology for having to ask. This increases the obligation to comply as you have now addressed any irritated thoughts by the other person and maybe made them feel a bit guilty for thinking them (as it seems clear you have 'found them out' for having such uncharitable thoughts).
A variant on this is to put the thanks before the request. This is not as effective and can be quite irritating.
Thank you for not putting your feet on the table.
By putting the thanks beforehand, the other person is initially confused and is more likely to feel deceived by the subsequent request. Having said this, this form of the pattern is common in some cultures where it is accepted as normal.