How do you decide how to remodel to get the best use?

[Ben Feder]

How do you know what to do, for example, for converting something into a master bedroom, or remove walls in a certain area, or any other type of restructuring or remodeling project where real estate is altered to fit a new purpose or design? Do you need real estate design expertise or lots of hands-on experience to know how to proceed? Also how do you estimate properly what the costs for rehabbing will cost in advance before actually hiring contractors?