You could go ahead and get expensive hobby paint, but I find I get better, more durable, results with standard spray paint you would find in a hardware store or even your Wal-Mart/Target stores.
Here's a shot of some of the pieces with a black top coat.
Here is actually the first skystriker that I painted. I don't think that I washed it well enough or perhaps it was too windy when I sprayed as there are several places where the paint either bunched up or didn't stick very well. I set that aside and opened another skystriker, washing very thoroughly before painting.
Here's the base for Thundercracker
Here's my first and second attempts at Skywarp. The one on the left was eventually turned into my Dreadnok Waspinator Skystriker. Bet you never thought you'd see those three words strung together. Post following on that.
Here's a profile shot of Skywarp, showing off his purple tail fins. This is the second color choice for the fins, the first purple I chose was too dark, whereas this purple is much more of a "decepticon purple."
I've got to take a moment here and compliment the skystriker's level of detail. It looks great in the normal gray that it comes with, but once you get a different color and in high gloss - the details just pop out. I don't know how much you can tell from my somewhat lackluster pictures, but it is awesome.
So here are my boys without stickers:
I used some pre-made custom sticker sheets and enlisted the help of a fellow collector with much steadier hands and much more patience to apply them. Here is the finished Thundercracker:
Here is my finished Skywarp:
And for comparison, here is the SDCC Starscream:
Here are the three seekers lined up. Don't get me wrong, I think the SDCC Starscream is a fantastic toy, but I knew I had to make my own after seeing the three of them together.
I liked the foil finish I got with my custom sticker sets, plus they had a shared style which was not present with the SDCC Starscream. Fortunately one of my friends needed the Starscream and I had another Skystriker! I painted the tail fins blue and got the appropriate stickers:
These guys look much better matched with each other.
Finally, here's a shot of my Skywarp with the corresponding Masterpiece figure. I think they look great together even if the purples don't quite line up. Yes, I do use these as matching figures - you can either go with the increased density in robot mode or mass-shunting theories if you feel the need to explain away the difference in size between robot and alt modes. Fortunately I'm not too worried about that.