Tip #1: I built my wing stand so that the spar is about shoulder-high. Only very little work is done above the spar (I finished the leading edge in a few hours) and everything else should be more convenient than working near the floor.
Tip #2: I found that the tank (and also leading edge) ribs installed easiest if the top clecos for all ribs were installed from the front to part way back, then beginning a few rivets back from the nose on the bottom. An awl is a great help to get things to align close enough to get in that first cleco. Just make sure the holes closest to the nose are close to being in alignment before pulling everything together.
Tip #3: I decided to do as much work as possible on the wing stand. That meant finding a way to support the wing outboard end and still getting the bottom skins on. A cardboard tube (similar to a carpet tube) worked out great. I plan to do all the riveting using this arrangement.
Tip #4: Oil the leading edge ribs and tank ribs when you initially install them! They go together MUCH easier. I used a light machine oil but would think almost any oil or light grease would work. I would stay away from WD-40 as it doesn't seem to lube aluminum that well, more like a cutting oil.
Tip #5: Van's say that most leaks on the tanks are at the corners of the baffle. I am adding small gussets on the inboard and outboard ribs to help seal the gap in those corners. The picture is of the end rib from the inside of the tank.
Tip #6: Absolutely the biggest time and mess saver is the syringe! I have used 12cc syringes for sealing the tank (after one session of trying to use popsicle sticks) and the difference is amazing. I mix the ProSeal on a piece of scrap aluminum (flashing left over from a home project) with a putty knife and use the putty knife to fill the syringe. 10-12 cc's is about right for a session. I added a couple of drops of MEK to thin the mix. The syringes can be reused! The ProSeal doesn't stick to them, and the next day they clean up easily.
Tip # 7: It is a time saver to install the flap and aileron brackets prior to installing the top skins.