So what you are saying is after pruning less than 1/3 of it, the branches will look the same, only the bush will be thinned out looking? Do I cut off the branch all the way to a nub? My Forsythia was propogated from an adult bush, two years ago, and it has a ' fountain' look to it. Is that how I should keep the shape? I notice I have growth off of these branches, should I prune them off to keep the fountain look?
New growth will not bloom. To optimize blooms, yes, you should cut the long, newest growth off. Depending on whether or not you have a newer cultivar, forsythia will generally look bushier and fuller if pruned; if you go all the way back to a joint, you should accomplish that easily (and the bush WILL recover), but just a few inches here and there to prevent those scraggly long new non-flowering canes from spoiling the shape (whichever YOU decide you like and your forsythia can handle) will do. I.e. the branches will be bushier looking but the bush's shape should be the same. I'm not saying cut every third branch off, rather cut every branch shorter by one-third. (Like getting a hair cut. You don't want your hair layered, just trimmed by 3".)
Whether to keep what you describe as a "fountain" look is entirely up to you and the particular cultivar of forsythia in question. If yours was bred to be a round little dwarf, it won't be happy as a big fountain. Conversely, if it was designed to be a weeping form, you will never be able to get it pruned into the shape of a ball or a hedge.
Hope that helps! I should have gone more into what to do instead of what NOT to do, I guess!