Hey,
Good topic idea!
As for what I am working on, I just finished up an Allosaurus, Pegasus and Dimetradon. As for future projects, I am not entirely sure although I have some ideas. I love Rays and Sharks, and basically almost all sea animals in general. On that note, I would really like to eventually make a few different sharks such as a Hammerhead shark and maybe one or two other unique sharks. I would love to do Manta Ray, and right now, I am just starting up on a Spotted Eagle Ray. I know that there is already a ray (Grin Reefer), but I think the Spotted Eagle Ray is different enough to make a custom, plus I think there will be some fun stuff done with the paint apps. Anyways, here's a pic of a spotted eagle ray:

I am also wanting to do a whole bunch of Dinosaur Battle Beasts. In my storyline, there is an entire side planet of Dinosaur Battle Beasts, with two distinct factions fighting for power. Occasionally the Dinosaur Battle Beasts and the Regular Battle Beasts coincide and work together. So far there is King Buster (TRex), Slag King (Pteradactyl), Tri-Horn (Godbeast's Triceratops), and my Allosaurus and Dimetrodon already. I would like to make several others including Anklysaurus, Stegasaurus and many more. Like I have said in my customs post, I would like to make an entire 26 figure series of Dino Battle Beasts, which is something I always wanted as a kid.
I am also planning on making several fantasy inspired Battle Beasts, even including many different styles of Dragons from different cultures from around the world. I was also thinking about a Unicorn, and several others that right now I can't think of.
Other than that right now, I am not sure what I am going to make. I think I am going to concentrate on the above three catergories for now: Sharks/Rays, Dinosaurs and Fantasy/Dragons.
As for any tips that I might give to other customizers, well, I don't think I have been doing it long enough to have the experience to really make any suggestions right now. Godbeast is a well of knowledge. I can reccomend however to use Water Based Acrylic Paints, Enamels suck! Marty also clued me on using Krylon Matte spray as an overcoat, but make sure to do even, thin coats from 12 inches away. If not, it gets tacky. I would also reccomend constantly scouring the toy aisles at stores to see other toys that might work to kitbash into a certain custom. I find that is how I get some inspiration as to what to get next. Well, that is what I have for now, as I get working more on my Eagle Ray, I will post more tips as I get to them, and also let you all know of my progress.
Eric