I'm in spray can he77

Sounds like a typical cause by humidity or flucuations in environment temperatures. Either can run havoc on spray painting sessions.

Get an airbrush.That is if you are sure you want to stay in the hobby long term,and get the most out of it,then invest in an airbrush and compressor setup,you won't regret it.

Check this guy out for suggestions

https://sites.google.com/site/donsairbrushtips/ 

Rattlecan spraying takes practice just like any other painting method.  Try practicing a bit before painting a model.  I know several model car guys who do a lot with spray cans and auto lacquers. They turn out great models. Good lighting helps prevent runs, showing an area that is starting to really gloss up, which happens just before a run.  Make sure you shake the full recommended time for each coat, and if it takes very long to do a model, shake every minute or two to keep all the pigment in suspension.

I still get runs with rattle cans.  I keep a good supply of very fine sandpaper.  I usually use #600 on runs, but if the run is not too bad I may go at it with 1000.  Then, I am just a bit more careful on next coat.

Thanks all for the good responses.  I can say that I was using questionable lighting for one of the coats (ok, it was in the backyard at night with minimal lighting!), and I did not shake the can enough.  I did use several grades of sanding boards to take out the bad spots (a big run on side of fuselage and some pooling along the ailerons) and the recovery isn't so bad.

I am hoping the that gloss coat I will use before decals and the final flat coat will help level some of this stuff out.  Oh, and look for my post in the Aircraft forum when I am done with the project.

Yes it's not easy. There's no control over what you get in the can.

We all grew up, well most of us, using spray cans to paint bike frames, wheel barrows, and other such stuff where you really lay it on thick. That's a hard habit to break.

I always plan ahead and get the cans at a good 75-80 degrees by sitting them in warm water.

When I paint, I try hard to follow the start ahead finish after rule. In other words, paint some air, go by the model entirely, and let off.

Keep it really thin. Multiple coats, and let it dry in between. One of many reasons it takes me centuries to finish a model is that I go anywhere from two days to a week, at indoor temperature, between coats. it helps to have a couple of models going at once.

I will echo what GM says above, regarding the heating of the spray can prior to spraying. I havent personnaly set mine in warm water, but I have brought my cans in from the garage, where I typically keep the rattle cans for storage purposes; however, prior to using I will bring them inside and let them set for a few hours (or a day or two) if I have a pretty good idea when I'm going to be ready to paint.

I picked up a rather cheap airbrush for my first time, just so I got used to it and made sure that it was something I wanted to invest in down the road. I think the combo kit I picked up off of EB for around $40 US and it included the airbrush and a small compressor. It wasnt the greatest by any sense of the idea, but it did a heck of a lot better job than just using rattle cans.

Since purchasing my the earlier airbrush, I have upgraded both my brush and my compressor and absolutely love what I can do. It just takes patience and PRACTICE, PRACTICE, PRACTICE!

I would not use sanding boards when sanding paint.  With very fine grit paper, it is essential to keep the pressure on the surface the same throughout.  Seldom is a model surface flat, but the sticks are, leading to pressure concentration and oversanding some areas and undersanding others. Even with wet or dry paper, do not fold the paper too many times, else you make it too stiff.  I love a fairly new product from 3M for fine sanding. It is a spongy foam, with little holes in it.  More self cleaning than paper and is quite soft so it is easier to maintain a uniform pressure on the surface you are sanding. The finest it comes in is 600, but I use a lot of the 600. It is just about the right grit for getting rid of rough spots and minor runs. It also comes in 400, which can quickly bring down major, thicker runs.