Some questions about Cellular and Signal Boosting

So I have no background in Cellular technologies, or RF in general. I've been given the dubious task of "boosting the signal" in the basement of a medium office building. So I've been doing my research and have picked up a test set. One thing confuses me.

I found on the FCC's website where I can look up the different band and frequency ranges of different wireless carriers in the area. But each carrier has multiple frequency ranges in multiple bands. How can I know what particular band/frequency range I'd be looking at to boost for specific users? Is it just a broad thing?

For example AT&T and Verizon for this zipcode all have at least one frequency range in the low 700s band, the high 700s band, the 800s band, and the 1900s band and the AWS band, etc.

What if I find the AT&T signal, for example, is really good in the one band but really bad in the other band?

It just seems like a nightmare of complexity and way outside of my wheelhouse. Any advice would be helpful.

We paid for a high end test set, so it should be fairly accurate.

But then figuring out what kind of boosting is needed is only the first hurdle. Then there's the whole realm of figuring out outside antenna type and placement (omni-directional vs directional?) and interior antenna type and placement (panel antenna vs dome antennta) and the media to hook it all up with, the settings on the Booster and how to figure out it's all working.

Any advice? Reading materials?

Thanks for any help guys 'n gals!