Yes, start small. Work your way up to things, and treat people well. They are the most important thing to your business. Even if you think they are young ricers who don't know the difference between a cold air intake and a short ram. My husband and I have been running the same kind of business out of our home since January. We still have our other jobs, but it is getting harder and more stressful by the day. This is actually good, because that means business is growing. I am very happy to say that our official shop will open in mid-October.
We haven't even advertised yet, and we have so much business we have to turn people down sometimes. When we open the shop, we will try to stock a little of everything. People don't like going to a shop and still having to wait on something to come in. They want it then. Just don't over stock and have items that will never sell. That's a waste of money and space. Good luck with everything!! Just remember no matter how busy and stressed you both get, make time for yourselves to spend together away from the shop.