Where do you draw the line?!?!

[Isaac Swan]

So I have I have posted this question on my Bigger Pockets blog, but I want as much feed back as possible. I just got into the first unit of my Four-plex, and its pretty bad. Well I think it is, first a little background this is my first rental property purchase and I am trying to slowly work my way into the investment property world. So here is the main question I keep getting caught thinking I should do all these things like knock out the wall to create a better floor plan, replace cabinet set to allow for more functional use of space, crown molding, floor boards, ect. My question is what is work it and what is not? Am I doing to much or is it worth the money and time?

As always any feedback is great! No suggestion is too small or too outlandish I wanna hear it all!