I have done a few jobs on the side, and do the best job I can. Doing it at home you tend to get customers that don't have the money to take stuff to a shop and want a lot done for free. I use to have them buy paint and I'd pick up the sandpaper ect and keep the reciepts. After getting cars that had a lot more work then was first seen, and people deciding ohh can you do this too, and this without mentioning any increase in money, and getting tired of buying materials for someone elses car, If I do anymore I would do it different. I would break down the work into so much time and when that is completed I get paid, and if anything extra is found that needed work, they would be called and it would added on to the bill. I wouldn't ask for all the money up front, but would from now on estimate material charges and ask that up front. Its too much hassle the old way I was doing it. Then when all is said and done, if the materials came up less then estimated could give some back or if more then estimated ask for the extra. With no money coming in and doing a lot of extra work for free its hard to stay motivated. Most people also don't realize how time consuming this type of work is to do a good job. Without money coming in and putting in a lot of time and finding extra work on someone elses vehicle you didn't estimate for, it is hard to stay motivated. With collision work, you kind of have an idea of what it will take and estimating guides and can make out. With an old car, or something where you are putting on aftermarket stuff, its harder to figure out what you will run into on the job. I agree they shouldn't be afraid to give you some references. I'll see how billing in time frames goes, If you put in a lot of hours, and don't have much money to show for it, you might as well work on your own stuff. There are also customers that don't pay or show up when its time to pay so it works both ways. I guess some contract between the two parties would be a good idea.