Which to pick: Investors or Loans?

[Johan Adler]

When is it beneficial to take on loans versus taking money from investors when flipping houses? I am an aspiring real estate investor who is interested in both investing in other flippers and also creating my own flipping business. Is it normal for a partnership to form between a house-flipper (someone who finds deals, buys property, restores the property, and sells) and an investor (brings in the needed capital to buy property)? If so, how does the partnership work, is there a norm in the percentages that the flipper makes versus what the investor makes?