The Practical How-To's of using an airbrush for modeling?

Well, for small parts or places that need just a quick touch of paint, like the cockpit walls, etc, I generally don't break out the airbrush either. I brush paint that. Like you, I hate having to put the time into the airbrush only to paint a small surface area.

I mix the paint and thinner in the paint cup, easier that way at least for me. I transfer the paint, relying on liquid cohesion. I put a tooth pick in the cup, touch the end of the tooth pick to the mouth of the paint jar and let the paint 'ride' the tooth pick into the cup. Since the tooth pick doesn't contain much surface area, there isn't much waste. No tooth pick? Use a straw or piece of sprue. Some guys use eye droppers, I don't tend to.

As far as amount of paint goes, I don't have a specific amount in mind when I paint. I general fill the 1/4 oz paint cup about half full (paint and thinner) then add more paint as I need to.

Hope that helps some.

The best advice is honestly to practice, practice, practice. Try new techniques. Experiment. Find what works for you. Dive in with a cheap kit and see how things go. 

As for your questions...

Painting smaller parts - I try to paint these in groups. So everything that needs to be interior green, or chromate yellow or whatever. Personally I prefer the look of airbrushed finishes to brushpainting, so I tend to airbrush everything I can then pick up details with the brush.

How much paint for 1/48 fighters? Depends on the airbrush. My Iwata sips paint, and I could easily stretch a big base color like neutral grey or olive drab (let's assume Tamiya 10ml bottles) out over probably two models, maybe three. My Paasche H, on the other hand, feels like it's halfway to a rattlecan by comparison, and could easily blow through an entire bottle on one kit. There's also going to be variance with notoriously poor coverage colors like yellow and white...but unless you're doing something like pre-war US schemes you probably won't be dealing with those in massive quantities.

Paint mixing? Depends on how much paint. For big coats on the main surfaces, I mix in glass jars. For smaller stuff, I'll mix in the cup if I'm using enamels. I've had bad experience with some acrylics where the pigments sink into the paint channel or under the needle before I can get everything mixed, so I use disposable 1 oz plastic dixie cups with acrylic.

I transfer paint with disposable pipette droppers. I use one for the paint, and one for thinner. Once I have the mix where I want it, I use the "paint" pipette to transfer the paint from the mixing jar to the airbrush cup. There's some waste, but it's minimal, and a heck of a lot less than spilling paint all over the place (kudos to those who can transfer with toothpicks and such...I tend to make a mess when I try that).

As for the trouble of spraying just one or two parts...yeah it's a pain. All I can say to that is 1) try to group them and 2) consider maybe building up two kits simultaneously that share some common elements. I'm building two WWII Soviet planes right now that use the same interior/gear bay, prop blade and underside colors. 

I generally assemble a model as much as I could before painting.    Some required separate painting include intakes, cockpits, gear bays, exhausts, I group them to color and spray seperately.  Sometimes on the sprue.

When transfering paint, I use a straw cut into several 3 inch sections and pinch the ends to hold the paint.   I mix paints in the cup then add thinner via straw.    Mixing is done by loosening the nozzle, plug the needle and press the trigger to "bubble" the cup.    Or sometimes, I simply use the straw to stir.   Or both.

Cleaning takes about 5 minutes.  Empty paint. Put thinner in cup.  Scrub sidewalls with finger. Spray until empty.  Put more thinner in cup, spay until empty.  Take needle out, wipe and check for bent.  Reinsert needle.   Once a month, I take the brush apart and give it a comprehensive clean with ennamel thinner.  Then polish the needle.  Reassemble.

There are a couple of good youtube videos on using an airbrush for 1/48 scale.  I think it's put out by a group called promodellers. 

There are also a couple of good videos on brush cleaning and maintenance by a bunch of manicurists. LoL.

brickshooter

There are a couple of good youtube videos on using an airbrush for 1/48 scale.  I think it's put out by a group called promodellers. 

Promodeller is a modeling business in UK owned by Phil Flory. You can find some of his early video on Youtube, including this Airbrush Basic.

He markets a line of premixed wash and modeling video that you can buy from Sprue Brothers if you are in the US.

brickshooter

There are also a couple of good videos on brush cleaning and maintenance by a bunch of manicurists. LoL.

Shiela McKenna is a wonderful presenter and her airbrush cleaning video is one of the best on the Internet.

double post.

 Really there is no "right" or "wrong" way to transfer paint to your brush. I have mixed in a seperate cup and transfered to the brush...... I have used a paint brush to cary paint to the airbrush cup......I have used pipettes. It is all a matter of what you are comfortable with. A little waiste is part of the deal but you should not have so much waiste that it would be a concern.

 As for painting a lot of small parts and repetitive A.B. cleaning. What you need to do is plan ahead. Unfortunately for you the model instructions do not lay out a clear path. What you need to do is plan out what colors will be applied to what areas. Devide your parts out this way and try to paint as many like colored pieces as possible at the same time.

All great answers and contributions, but I must second Iain. You must plan ahead, I usually check as much as I can those parts that requires the same color. If the cockpit tub and related parts go the same color, I put them together and laid them aside so they will be ready when I'm ready to paint the cockpit walls and so on.