Question: How to make deals in crypto currency?

[CoinsAreBubble]

The question is following:

How to make deals in crypto currency?

As I know signing a document gives nothing, because it has no legal effect. I provide some services and it is a real headache sometimes.
Deals with < 1 BTC are completed with no problems. But if it is much bigger, here comes the problems. I can't change the type of payment. There is no fraud. Clients which I know in person do not ask such questions or have some mistrust. But if we don't know each other and he contacts me for service, there is a long conversation with no result. I want to break this wall.

Have you dealt with such problem? How did you solve it?
I would appreciate it if you could give me some advice. Thanks.

[Zwei]

Have you dealt with such problem? How did you solve it?
I would appreciate it if you could give me some advice. Thanks.

i think using an escrow that both of you trust will be the best idea in this cases.