How should I go about renovating a house? and when is too much?

[Joey Soewargo]

For example, I found a great house --and I mean great from a fix and flipper's standpoint-- in a great location covering 937 Square ft, but the house has no appliances among many other things. When calculating costs in order to get a profit, what is the threshold in which I am adding unnecessary expenses. Should I plan on getting new appliances, used, or standard appliances that serve their purpose? Or would this be something that the buyer worries about? 

I'm also curious about paints I should use --for cabinets, walls, etc.-- and also when updating the kitchen, how do I go about updating the counter tops i.e granite, marble, tile. As of right now, the kitchen is entirely wooden, which from what I've heard looks and is undesirable.

The carpet as well seems to have taken a lot of damage so how would I go about repairing that, or when should I think about changing the flooring to porcelain or tile (considering it's in the kitchen)?

I was also seriously considering replacing the window AC units with central air because I think that would help increase value but it's also added expenses.

I'd like to hear your guy's opinions and experiences as fellow wholesalers. Any input and constructive criticism is also welcome as I am trying to eat up as much information as I possibly can. Thanks!