I live in a small apartment.  The property owners are not required to compost, so I really have nowhere to collect or dispose of food waste.
Due to space, I am also not able to warehouse the plastics that aren't allowed in our collections dumpster.  When I had room, I took this stuff to a depot.
The most frustrating thing is seeing non-recyclables in our collections dumpster - plastic bags, styrofoam, clamshells, etc.  Wish-cycling materials!

A friend gave me a lightweight fabric bag that crams into a little pouch.  I used a small carabiner to attach the bag (in its pouch) to my purse.  When I need a bag, it's at the ready.

This is pretty easy since I work for a company that takes sustainability seriously.  I personally generate quite a bit of single-sided documents (due to the nature of each document being only one page long).  This material is dated, and when it's no longer needed, I print another set on the backside of an earlier set.  

I do use the plastic produce bags from the grocery store, but I use them more than once.  When I get home, the fruits go in a hanging basket, the vegetables get used fairly quickly.  So, the bags are re-usable.  Maybe I have to hang them up to dry before the next use, but then I just put them with my cloth shopping bags so they are ready for the next trip.