once you've taken the varnish off, halfords car primer (something i used on mdf) would be a good choice. It doesn't taken long to dry and you can see inconsistencies in the area and build that up. I used car body spraypaint (over the primer) and you can, using a very fine grain sandpaper rub down between coats.i'm not sure you can repeat this with lacquer (i did this 4/5 years ago now, cant remember if i did.)
best tip i've had when spraying is not to do one side, leave to dry and then turn it over, but to hang it in mid-air and do a series of quick short sprays to prevent it running. where it seems like it might be a larger surface area you are spraying - maybe try hanging it horizontally and spray vertically. if you dont keep the pressure of spray consistent, don't try and build it up then and there as you'll probably over-spray and it'll take alot of effort when sanding down. instead, leave to dry and then add another coat. repeat until you're happy.
this is what i was taught and the work i did turned out pretty well. good luck with it.
mew