I'm running an LLC... should I cut myself a pay check each month?

Well it depends on what type of LLC. I'm going to ume you are a single member LLC and did't request corporate tax status. The IRS considers you a "disregarded entity". In other words you and the LLC are one in the same so you only have one income stream not 2. You do not issue yourself a payroll check - you take draws. At the end of the year the business net profit is your income on which self employment tax (social security and medicare) and income tax is calculated. Yes you pay estimates throughout the year.