Managing high maintenance clients - how do you do it?

I have a few clients that are pretty high maintenance. They call themselves entrepreneurs, however the couple of entrepreneurs I work with have a few common characteristics. They are usually time poor or seem disorganised, they have massive ideas and not enough resources, they need everything yesterday.

I like the work as it is usually pretty unique and innovative however I do find these high maintenance clients are pretty demanding and I feel like I am having to be really assertive and stand my ground more than with my other clients who are fairly simple to work with.

At first, my reaction was that they weren't a good 'fit' however I do like the work and concepts and the fact they are completely unique so I am continuing to work with a handful of clients with these characteristics.

I have started to do the following for this sub-group of clients:

- clearly outline every element of the project - in finer detail than usual
- get quotes and outline in detail each and every request they have sent me via text or phone call so we have a paper trail
- cc their team so everyone is in the loop
- set guidelines for when I am available (i am not willing to do their work 24/7)
- get them to outline a list of tasks in order of importance

Is there anything else I should be doing to ensure projects are managed and everything runs smoothly. The level of urgency for almost every task seems to increase with these clients and while I can accommodate this, I do have to ensure that I am not 'working' for them but providing a service that I am in control of.

Any tips?