I've never done it myself, but I have a few thoughts.
In 2015 small business marketing is 1,000x easier than the old days and can be very cost effective.
(1) Social Media: Create a Facebook for you consulting business. "el_nino101 Bodybuilding Consulting" or something like that.
(2) Utilize social media even more. Create YouTube videos (set to private) give new clients access to video demonstrations, taped nutritional plans, or whatever. Instagram, Tumblr, LinkedIn, etc... are all free. I follow a ton of people on Instagram like Mark Bell, Brandon Lilly, etc... and have bought products from them after seeing it on instagram (Ex. The slingshot hip circle thingy, which I love for warm-up). They're great marketing tool that cost nothing.
(3) Create a free Gmail account for your business. "email@example.com" or whatever (I would personally use my full name). You can also use Google Docs for all your training and nutritional plans, which will also allow you to share the plans seamlessly with your clients.
(4) Business cards. You can print business cards fairly cheap these days. Add all your social media links and contact info.
(5) Create a website (optional). If you're talking about a small number of clients I wouldn't waste the money, but if you want your consulting business to really take off it might be worth the investment. Research domain costs (Think GoDaddy).
Just some thought. Hope it helps.