There are several ways to turn your trains around: the reversing loop, the wye, turntables and the ol' reliable 0-5-0, in decreasing order of space required.
A reversing loop is pretty simple, it just requires some special wiring but nothing overly complex. It is the least prototypical (rarely one finds something called a "balloon track" in real-world railroading) but easy to disguise as something else, or a way to make your blobs work double duty.
A wye is fairly prototypical (they are found often on the prototype) but their operation on a layout is a little trickier: instead of running through and throwing one switch, a back-and-fill requiring several switch throws is needed. They're nice near yards or branch interchanges.
Turntables are mechanically a little more work but ideal for small spaces. They are less necessary if you use locomotives that don't need to be reversed (center-cab diesels etc.) but they can be handy. Obviously you can only turn one car at a time (maybe two) but generally freight cars don't need to be turned, you can just store the train in a yard track, reverse the locomotive, re-spot the caboose and then go back to the new front of the train.
