Somewhat depending on the business. Mining is different from social networks is different from clean tech :-) For software, something like:

1. Salary/Benefits. 2. Marketing/PR/Sales. 3. Rent/Utilities/Facilities.

Everything else is likely a variable cost you can pay with customer money, aka "revenue." (Anything from direct sales to ad-based monetization) Once you can in addition pay the above three from revenues, you should probably stop taking investor money and look for liquidity.