Painting question

For the most part, you'll want to assemble before painting. Painting the parts first can lead to damage to the painted surfaces when you glue them together. The only exception is when assembly obscures another spot on the figure, in which case, you would want to paint the obscured area first, then attach the other part and paint  it. That advice is pretty universal to all models.

Thanks for the advice plymonkey. I'll probably be writing some more questions as I get more models.

if the figures are to be primed as some people do

i don't be some people do

 you could prime them while still on the sprues

i do paint the primary color while still on the sprue then if required i touch up after assembly

In most cases you're better off building first, for no other reason than most of the time there will be a gap between the arm and torso which you might want to fill and sand. It's really difficult-- and somewhat counterproductive-- to fill and sand after painting (you end up repainting things you've already painted). If you're converting the figure, i.e. adding an arm or leg from another figure, it's almost a given there will be some trimming and filling. I usually add equipment, weapons and other gear before painting, too; there is usually some trimming or heat-forming to be done to make the equipment fit better, or to get the hands to fit around the weapon.

Hope this helps. 

This process works for me

1. assemble, fill gaps, and sand the torso, legs and arms of the figure.  I like to leave the head off for base painting if seperate from the torso. 

2. Prime the figure with white or grey primer.  This highlights any imperfections in assembly.  Prime the head and any accessories as well.  This includes weapons, packs, pouches, etc. 

3.  Correct any imperfections in assembly and reprime.

4.  Paint the figure and accessories base colors and skin tones 

5.  Scrape the paint and primer from where the figure and accessories (head too) will meet, and tack the accessoreis on with CA glue. 

6.  Detail paint, highlight, and weather the figure. 

7.  Enjoy a Diet Coke.   

This works for me, but everyones methods differ.  I should add that I'm not the very best figure painter, but figure painting is alot of fun.  Many guys are needlessly intimidated by figures.  So kudos to you for diving in.