Expense tracking for a house hack

[Jeff Prather]

I did it! I bought a duplex. I'm living in one unit. I'm renting the other. 

Now, I want to be proactive about the bookkeeping so that I don't have a nightmare at tax time. Here is what I want to know. 

I set up three new accounts for the property - 1 checking and 2 savings (one savings just holds the security deposit and the other will be overflow from the checking. I'll keep a certain buffer amount in the checking but then I'll transfer anything over that to savings). I set it up this way to avoid co-mingling of personal expenses with expenses for the property. I have not set up an entity so this will go on my personal return. Here is the problem: its impossible to avoid co-mingling with a house hack!

I've already put money into the property and I used my personal accounts to pay because it wasn't strictly for the tenant side only. The money has been for things like junk removal and cleaning of the crawlspace, home depot supplies for yard projects, landscaping, ect. I know if I consult a qualified CPA at the end of the year they will tell me how much I can deduct and I plan do do that. For now, for my own tracking purposes, I'm trying to wrap my mind around spread sheeting the expenses and determining which accounts to pull money from to cover them:

How will deductions work since its part dwelling for me and part investment? as a general rule, would I just deduct half of my expenses? 

Should expenses be taken out of the investment property account or my personal account?

How can I expect the purchase to affect me at tax time? I understand that buying a house should, as a general rule, positively impact me at tax time. Is there a way for me to quantify that and adjust my w-4 deductions (from my 9-5 job) accordingly? I'm a big fan of tax planning and estimating throughout the year what I'll owe. The last two years, I've paid an additional $100 in taxes at the end of the year combined. Its been fairly simple though with just a federal 1040 from a single w-2 job and no state income tax - Thanks Tennessee!!

I'm open to any suggestions that I can implement today to improve my systems and make my life easier in the future relating to house hack. Thanks all!