I bring my make-up bag everyday. I started doing this because sometimes I'd end up staying the night at my fiance's or my sister's house without planning it & id need my make-up for the next day.
It contains my studio fix powder, concealer, eyebrow pencil, eyeliner, mascara, lipbalm, a brown and highlighter eyeshadow & gold glitter, tweezers, tissues, wet wipes, cotton buds/q-tips, spare hair elastics and some other bits and pieces. For the past few weeks i've been carrying a choice of 1-2 lipsticks, 3 glosses and 2 blushers.
If im going out at night to a restaurant or something and I know for definate im comin home, I just carry my lipstick/gloss, eyeliner, foundation & cotton buds.
Oooh and as for brushes, my make-up bag always has a powder brush, my 187, eyeshadow & blending brush.