These days I have to be even more organized when I go out. That means thinking about naps, feeds and diaper changes each time I plan on leaving the house. Pair that with hauling a bag filled with diapers, wipes, extra clothes, a portable change mat and anything else we may need when not at home. It was a pretty difficult adjustment at first, but now I feel like I have it down pat (most days). Something I put together recently was a little emergency kit that I carry in my bag at all times (note: not a diaper bag. I just can't do it).
I bought a small toiletry bag from MEC and filled it with some things that I may need when I'm out and about. Included: Purell (I'm not totally sold that this stuff actually works, but it makes me feel better in a pinch—like on the subway), kleenex (snot, puke, you get it), Mustela cleansing cloths for babies (I use them instead of wet wipes), a bottle of water for emergency hand-washing in parks or when eating outdoors (I hate not being able to wash my hands before eating or feeding Maxwell), and snacks!!!
I grabbed all of these from MEC too. I'm not one for energy bars, but sometimes I have no time (or forget) to eat and I feel better knowing I have something I can scarf down fast if need be. Also, I was pretty intrigued by the selection of "energy chews". I'll let you know if they work!