Accounting on Excel, what am I missing?

[Aroldo Villarreal]

I have been looking everywhere for an excel template for keeping track of my expenses, income, and reflecting monthly cash-flow for my SFR investment but have not found anything that suits what I'm looking for, so I decided to start my own. Disclaimer: I have no idea what I'm doing. With that out of the way, these are my questions based on the columns I have.

Income:

I have my rent as my only income (plus late fees if any). Is there anything I'm missing?

Expenses: (each of the following is a column)

Mortgage - same month per month

Taxes - same month per month

Insurance - same month per month

Other Expenses - repairs that come up

Reserves - Amount I put aside every month for repairs and save up for capital expenses (roof, windows, etc.)

I don't have a "management" column since I am managing it myself. 

I have found in spreadsheets that "Principal" is NOT considered an expense. Why?! Also, if principal is not considered an expense and interest is, am I supposed to have a column for principal and one for interest and then go in there every month and input it? I'm assuming it would basically look like an amortization table if I do this. 

Deposit

I don't know where to, or if I should, put the Deposit I received.  - Since I can't really spend it, this is not income at all, correct?

My goal is to see an exact amount of money that I can either use to spend (not likely) or put back into my investing account to save up for the next properties. Any in put would help. Thanks!