Again; if you're trying to do a Gibson type dark red finish; black filler would be the norm, per the pics above; here's a link to a step by step of applying that finish to a Tele Thinline.
If you're trying to do something completely different, you need to give us more info, examples:
- If you are going to paint the body any kind of opaque red color, it doesn't matter what you use for filler.
- If you want like a bright red filler and some other coloration like a "Voodoo" finish, please specify