When to paint?

I personally never paint any parts on the sprue ever as once you remove the part and trim and sand it flush you then have to touch up the paint in that spot.

I remove them from the trees, trim and sand them smooth and then hold them with a toothpick in an opening in the part or with an alligator clip attached to a piece of wire, etc.

When to paint parts is a personal thing actually and we all do it a little bit different.

I personally like to look through the instructions and find every part that is a certain color so that I can airbrush them all in a group and then put them in a plastic parts organizing container and use them as needed.

As well as looking at what individual parts can be painted as a group in the same colour (as Mike has suggested above), look at what parts can be assembled into sub-assemblies which are a single overall colour. 

excdn11 wrote:

I noticed that some people paint some parts on the sprue, is there a general rule when to do this and when not to? Im just back to the hobby and any tips would be appreciated

I can think of one situation in which I would paint the parts on the sprue: 1/72 tank road wheels.  They're so darn small that you really have to paint the tire portion by hand after painting the rim and center, so in this one instance I find it to be convenient to leave the parts on the sprue which makes holding them whil painting a LOT easier.

So typically, I would clean as much of the molding line as I could before painting.  Spray, and possibly camo the wheels.  Then paint the tires with a small brush.  After all that is done, I would clip the wheels from the sprue, clean up the attachment points and do a bit of touch up on the tires.

As for the rest, i.e when to paint, some of that depends on you own skills.  As an example, if you build a tank, it will have a variety of tools on it.  Some modellers find it easier to glue on the tools, paint the tank, tools and all, and then carefully paint the tools.  For me, I find it easier to paint the tools separately from the tank and carefully glue on the tools later.  The main thing is to think through your assembly and painting prior to doing it, and do what you feel the most comfortable with doing.

Andy

I think most people would simply follow their own personal preference.  If you know there is going to be a lot of touch-up it makes more sense to paint the parts after final assembly or at least after removal from the sprue tree, clean-up, etc.

However, I build planes and I always pre-spray all of the interior and as much of the cockpit pieces as I can while on the sprue tree because if you weather the interior at all, there is not much to any small degree of touch-up you may need and nobody would be able to discern a brushed up spot anyway.