Keeping track of my business

I understand that I need to start saving receipts for anything and everything that I could possibly justify as a shop/business expense but I am wondering about fuel costs.

Having a few different vehicles and using them for more than just business purposes has me confused.

I do not mind pushing the envelope but I do not want to try and claim anything that is going to send up a red flag with the IRS so how do you guys keep track of your fuel costs?

I have been spending alot of time on-line figuring out the quickbooks, I ordered an older version of quickbooks (that was cheap) from E-bay just to get even better familiar with how the software is used ( cause evidently it really has not changed a whole lot at its core ) but can you guys that use it give me some examples of how you keep your receipts?

Once I am more familiar/cofident with how it is used I will order the newest version.

Assuming you have separate folders for fuel receipts, another one for shop improvement expenses, maybe another one for shop equipment ect ect but Id like to verify and hear what others are doing.

How about the building in which I am renting for the shop, I have put a tremendous amount of labor into the building, I understand that the materials are deductible ( if I had bothered to save the receipts ) but how about my labor?

I had to build within the area a minimum 100 square foot office space ( as an example ) to be compliant with the requirements for getting a dealers license ( which I am still working on ) and so that took alot of time, seems to me that I should be able to claim something for that but according to the accountant that I am considering to use I cannot. If I had to pay someone to come in and do that office space I am sure the bill would have been approx 6000 dollars.