Brent my recommendation is following the advice already given by Mark and Andy. I'd use 80 grit "emery cloth" (known strangely under different names like "shop cloth" when trying to find it from suppliers - emery is a British word). I buy it in 1" widths. Before scrubbing the surface so the paint can adhere better, I'd mask the lugs. Even when being careful, it is easy to mistakenly scratch the lug surface when roughing up the surrounding areas. I use an Exacto knife to cut the masking tape I've tried to stretch tight over the lug. I have to resharpen them all the time. I use many pieces to cover one lug. Just for reference I often sandblast the areas near the lug after coving the lugs with duct tape. It isn't necessary to get exactly up to the lug.

I use House of Kolor epoxy primers for several reasons. 1st of all they come in the 3 primary colors as well as black and white. By mixing them I can get almost any color. That way paint chips (often between the color and primer) are less noticeable. Furthermore it can double as a sealer (by adding more reducer) between sanded primer and color coats. In addition it is very sandable. A painting tip is that I always use the slowest reducer 312 (designed for the hottest conditions) when thinning the primer no matter what the air temperature is when I'm spraying. It flows out better.

Dynafiles should be used with the greatest caution. So much can go wrong so fast in unskilled untrained hands. I seldom use mine and I'm really good at knowing how to handle it. I never use it for any final work, just to get gross stuff off. I was chatting with my colleague Jeff Bock yesterday about Dynafiles and said I don't ever let students use them any more. My example was a frame building student back in the late 70's that I gave him one to thin his lugs. He was so delighted in how fast it took off metal until he noticed he had gone so far his silver brazing material was showing having completely gone through the lug. One safer method to tidy up fillets - after shaping them with hand files - is to wrap some emery around a steel shaft attached to a drill. I slot the shaft to insert the end of the emery. This technique works but not too quickly like an 1/8" Dynafile belt. The shape of the wrapped emery can be created by the size of the shaft and the amount of emery wrapped around. It is easy to get to new enemy by just tearing off the end. Even this more gentle method should be used with great care and only after practicing on practice fillets 1st. By the way it is also a good way to clean inside tubes or lugs before brazing.