The simplest way to do a guide track, is simply to record the vocals for a song, along with one accompanying instrument (maybe guitar or piano). These parts don't need to be recorded well enough to be used in the final recording, but they would need to follow the same structure (length of sections and order of sections). These parts can then be recorded again once other parts are laid down (usually the final drum and bass parts would be recorded first, as they provide a strong basis for recording other parts).
If the timekeeping is excellent in the guide parts, and the players recording the parts are very familiar with the playing in the guide track, you could record the guide track without a click track. This can give a very natural feel to the timing. However, it would be safer to include a click track alongside the guide track. This is also useful in modern recording, as most recording is done using software which aligns recorded tracks within a framework showing the bars and their subdivisions. In fact, the simplest kind of guide track is just a click track, with maybe vocals or somebody calling out sections.
In the end, the most important elements a guide track needs are: good, clear timing, that other parts can comfortably play with; clear outline of the overall structure. Some of the best guide tracks I've worked with are simply one performer playing acoustic guitar and singing, with a loud click, and (as you suggest) calling out and counting in different sections.
Finally, it's worth noting that modern studio software means that you can change the structure of a song after material has been recorded, as you can edit tracks to move sections of tracks to different positions within the song. But it is certainly quicker, and easier to create a "natural" feel to the recorded parts, if you stick to the structure recorded in your guide part.