Since nobody has offered any help/opinions up to now, I guess I will take a stab at it, even though I must declare at the outset that I am not a professional product photographer.
First; you need to "network" with anybody and everybody who is either doing that work now, or needing it done. If you have manufacturers or wholesalers in your area who might need good photos, (see what they're using now) make a cold call.
Before you make a cold call, have your portfolio to include some (good) photos of anything similar to your target client. If it is something round and shiny, make sure your portfolio has something round and shiny (done well) and then point out to them the deficiencies in their current photos, and sell your services as someone who can deliver a better product.
I assume you have been studying how other photographers do it, so do it like that. Set up your product and shot in a way that really does justice to the product. (appropriate setting, angles, lighting, etc.)
Make some prints to show when you are visiting in person, and have a few sample shots standing by for e-mail communications. Don't shoot the exact same product as you are soliciting for until you have a contract.