I've seen the practice of using queries in forms. Is this recommended? Why?

That is... I am pretty much making data entry forms and am basing them off
of the tables. Should I be making queries of these tables and basing the
forms off of these instead?

If so, should this practice include "look up tables" (tables that I'm using
in multiple combo boxes for multiple fields on the form - they just have an
ID (primary key) and a field for categories such as "0-25%", "26-50%", etc.)?

Thanks,

Jill