What are loans doing in this list? Loans aren't compensation, are they? Well, the answer to that is that they often get reclassified as compensation (or, worse yet, as dividends) by the IRS, so you may as well think of them in that context from the get-go. Then you'll be motivated to avoid the pitfalls that cause this reclassification.
The temptation for a small business owner to use his company as a bank is a mighty one, and one to be mightily resisted. The owner of a closely held corporation is able to borrow from the company on favorable terms and repay when convenient, two considerations usually absent with outside lenders. Going the other way, an owner can also make loans to the company and earn a self-determined rate of interest. And the potential for the abuse of these powers is what inspires the IRS to increased vigilance on this topic.
Loans, in order to elude reclassification, must be documented in writing, have a set repayment schedule (which is adhered to — not just a pretty chart to hang on your wall) and an interest rate that can be considered consistent with the going market rates charged by third parties. Below-market or no-interest, "on demand" loans just won't hack it. The IRS will "impute" interest at the market rate if you fail to do so. This means you'll pay tax on an amount of interest you never even received!
And don't even think of living off of periodic disbursements from your business which you "think of" as loans. You'll get taxed on them, perhaps even with payroll tax penalties, and your company won't get a corresponding deduction. Many owners, in tough years, try forego taking a salary and just "borrow" enough from the business to live on. The audit risks are significant and not worth it.