I thought I might share the little trick I have when it comes to priming models. I use a combination of spray priming and brush priming.
A while ago, after much trial and error, I found two things... a good, black spray paint and a cheap black bottle paint that are exact matches. This allows me to spray prime most everything I paint and then go back and touch up the areas I missed with the bottle paint.
It also allows me to go in as I'm working and clean up and mistakes I made without having to worry about the colors matching.
Now this won't work when I use other techniques like priming with different colors similar to what I did with my Lustwing to achieve a certain feel to an army.
This really comes in handy with models like the drop pod where I can paint large areas, work on them and then go back and clean up the edges where paint may have gotten on the wrong part.
Another nice feature of this particular combination (of brands of paint) is that it works great on resin models like the Forge World drop pod I'm working on now. A simple wash with soap and warm water (of course there's more to getting resin prepared to work with) and there's no problem at all getting the spray paint to adhere and leave a nice, smooth coat to work with.
Here are a few more links on priming models:
Things to consider when priming
The actual process I use when priming
And the definitive guide to building and magnetizing a drop pod.
Additional related links:
Cleaning mold lines off resin and large models
Washing resin models prior to painting