Soon to be visitor looking for subway info. in Shanghai

I'm looking to get a pulse on best strategy for using subway in the most affordable way. Will be in SH for 3 weeks and would like to use the subway as much as possible. Is buying the Souvenir pass anything more than a tourist gambit? Is there a multi pass that would work, still working out details but will be staying near SH U of TCM (southeast part of the city I believe). Any ideas, things to look out for or any ideas on how to make my stay not so touristy and more affordable that would be great!