Yep, Will, that’s it in a nutshell.
Just fill an air-tight container with 91% isopropyl alcohol from the pharmacy, put the locomotive shell (without any clear parts) in for anywhere from 30 minutes-1 hour. Take out, and scrub the paint off with an old toothbrush. The parts won’t be harmed, and you will have an undecorated locomotive.
Then, detail to your heart’s delight, and then use a rattlecan of paint.
Use a primer, then Paint the silver first, mask that in the pattern suggested by the decal instructions (aim for about 50% of the stripes) and then paint the red. For masking the curves, you can take some 2" wide Scotch blue painter’s tape, and trace the curve’s lines out onto the tape. Cut it out, and place it where it needs to go. Then, mask as normal.
Lay the decals down, and use your favorite decal settling solution (like Micro-sol from Microscale) and then wether to your liking.
I tried searching for some BNSF Warbonnet decals for you from Micromark, but I just came up with pre-BNSF merger schemes for the Santa Fe. You may be able to piece together the BNSF letters from another decal set.
http://microscale.com/Merchant2/merchant.mvc
I, too, am a teen-ager in the hobby, and I know what you mean when it comes to having to be cheep.
Keep us up-dated on this project, as I’m interested in how it will come out.</