When it comes to investing, cash is king. So don't be surprised if your investor asks for the lion's share of the equity. That said, your expertise is also valuable -- otherwise, the investor wouldn't want you as his partner. The reality is that deals like these vary all over the map -- from 50/50 splits to 90/10 deals in favor of the investor. Assuming that you're willing to forgo a salary until the business starts making a profit, you can typically negotiate a much bigger equity stake.