Please post any tips or resources you wouldn't mind sharing related to painting aircraft in this thread.
One of the best resources available is The Simmers Paintshop http://www.simmerspaintshop.com/
There are many tools available on this site. Be sure to look at the site navigation on the top left of the main page. You can find paint colors, down-loadable markings for many nations, fonts, etc. If you are new to painting, I would recommend down loading a template or two to look at how they layout their templates. Can be real useful if you are new to working with layers.
Another place to get markings is here: http://www.regshanger.com/Groundcrew...e%20Decals.php I have been using these for years!
Here is another site I have been using for references for panel line locations and possibly for rivets also: http://www.airwar.ru/other/draw.html The site is in Russian (I believe), but you can navigate around it pretty easy. Not every plane represented on this site has good quality drawings, but there are some that are of great quality and very useful.
This modeling site has always been a great source to inspire me to do some paints: http://modelingmadness.com/
Another modeling site that can be useful for inspiration. http://www.ipmsstockholm.org/