Since it's winter (obviously :D) here's a little "guide" to what to wear in different occasions:
Going to work, I think you should be well dressed & look responsible so forget about the massive cleavage and short dresses. Opt for simple yet chic looks; blazers, scarves... & don't wear too much make up.
if you can wear heels for 4 to 5 hours (cause that's how long it takes us girls to shop ;) ) without your feet hurting you then go for it, if you can't then flats or platforms are the answer.
TO RUN ERRANDS:
Same as going to work.
Leggings, knee high boots and tights with short dresses & loose tops.