A word of warning on an old #4 or #5 as a first plane. Without a frame of reference, how will you know whether you are tuning it properly or when you've reached "good enough". My struggles triggered the following cautionary diatribe, with equally passionate responses:
http://www.sawmillcreek.org/showthre...ith-old-planes .
6 years later, I almost never reach for that #4, favoring the LN 102 Low Angle Block, Lee Valley BU Smoother, or LV BU Jack. If I were doing it over, I'd get one of these, first. Or, if you can, as others have said, find a mentor/coach/club, try out a few and make up your own mind.