How to estimate home values before and after improvements?

[Dale Couture]

Forgive me if this has been answered somewhere before...

I am planning on getting into real estate investing in a few years once I finish paying off my student loans. In the meantime, I am trying to learn as much as I can about it. One of my main questions currently comes in the realm of home improvement. I am thinking of buying a single family home for my first investment and I would like to buy something that I can make moderate improvements and repairs to and see a ROI on it.

When looking at real estate listings, without paying for an appraisal for each property, how can I look at a home needing some TLC and estimate what it will be worth before and after repairs and improvements are made? Is there a guide or calculator somewhere that estimates these sorts of things? I am sure every case is a little different. I just need some guidance on spotting the right opportunities out there. Thanks!