How much do I set aside for expenses in Texas?

[Austin Copas]

Hello, I'm Austin I was wondering how much money I should set aside every month for the different utilities and expenses. Since I am too young to legally own a multifamily property myself I am going through LoopNet and running the numbers on different properties to find deals for practice. I have a spreadsheet that I made with different utilities and expenses that include taxes, insurance, water, sewer, garbage, electric, gas, internet, lawn/snow, HOA Fees, vacancy, repairs, CapEx, prop. management, mortgage. I was also wondering what are the best ways for the tenant to pay for these utilities because I saw a few ways such as a flat rate or paying for only a few of the utilities? This would really help me and thank you for the help!