Use woven fabrics only. Knit fabrics are not appropriate to this design process.
Use simple woven fabrics. You can use leather, corduroy, cotton velvet, or other napped fabrics; but I would wait until you have more experience with this design before venturing with fabrics that require special layout, cutting and sewing techniques.
I suggest using natural fibers, or those blends that are primarily natural fibers. I recommend linen, cotton, rayon, or a combination. Prewash and iron if needed before cutting. Most natural fiber dyes WILL run and shrink when washed for the first few times. I have had linen continue to run their color onto other items even after years of washing, so I'd suggest not making a two toned garment until you are familiar with the fabrics you are working with.
Wool will shrink even when laundered properly. It is probably not a good choice for first attempts, unless you plan on dry cleaning.
Silk is not a good choice for new sew-ers, because the material can slide a great deal when both cutting the fabric and then during the sewing process.
Most people assume that dyes were not available for any colors except earth tones — browns, tans and the like. I am not an expert on the subject, but I have seen rainbows of colors produced by natural dyes in displays at Kingdom University and other events.
Have fun! Use bright colors, or dark, or whatever you choose. I prefer using the colors you see in nature — flower tones, yes; but also ruby red, ocean blue, forest green, the golden yellow of the sunset. Other than advising you against electric tones (I don't think they flatter anyone), I would not presume to advise on color choices. I would advise against using prints until you've had the opportunity to research and decide that which would be appropriate for the garment you wish to make.