You’ll probably need high resolution (large) textures, especially if your model is going to be close to the “camera”.
Remember that bump / normal mapping won’t add detail at the edges of the model. If you need such detail, you’ll have to use a displacement map or model the geometry.
Go easy on specularity; you’ll find almost nothing in the real world reflects light like that. Reflection and gloss are usually more realistic-looking, though they take longer to render.
Are you doing the lighting of the model as well? For compositing 3d into a real scene, matching lighting is even more important than textures. You need to take into account colors of the lights in the background plate, get the shadows correct, add indirect lighting, etc. It’s even better if you can be at the live-action set and make lighting notes or better yet shoot footage of garden spheres or ping-pong balls on the set, so you can match the lighting on 3d spheres. All of this will interact with your textures, and round and round you go.
Finally, look up stuff by Leigh van der Byl; she’s one of the best CG texture artists around. Best of luck with your project!