Zenithal priming is a great technique to use no matter what your skill level. Basically this is how it's done:
Once your miniature is assembled and cleaned, prime your miniature using black primer. It's really easy to over do it with primer so go slow. The black primer is going to be part of our paint job though, so you want solid coverage, not just the light dusting of primer that some folks prefer. When you are done with this step your model should be black.
If there are cracks that are hard to get paint into with the spray can of primer, wait until the spray primer dries and get those spots with a paint brush and brush-on primer. Don't be afraid to load up your brush and stab it into the cracks.
If you don't have any brush-on primer (you should get some, I like Reaper Master Series) you can "decant" some of your spray primer by spraying it into a cup. Hold the spray can very closely to your cup and spray until you have what you need collected in the bottom of the cup, then apply with an old paint brush.
Whenever you spray paint you need to use proper ventilation and/or wear a mask:
|This is a great mask, it will protect you from just about any hobby chemical you can throw at it and it won't fog up your glasses. I even wear it if I have to do a lot of gluing. Check it out: http://amzn.com/B00004Z4EB|
|See the "shadows"? I went pretty heavy on my application of white because I wanted to start with a lighter base coat.|
If anyone has more Z-priming tips or other tricks please share them in the comments!