I usually dress appropriate to the seasons. I like my avatar to have jackets and scarves in the winter and swimsuits/shorts in the summer. Formal wear is year round as inspiration hits me. I really enjoy dressing for holidays/events.
Usually, YES I dress for the seasons. I have specific avis that I only use in certain seasons. Fall, Winter etc.
I also dress up for holidays. Currently I am working on 30 days of gold shop and free grant only avis so they might not be as fancy as they were before but they're still gonna be themed for holidays and such.
I sometimes dress for the season or holiday/event depending on my mood. If I am not in the mood or if I am just being too damn picky on what I want, then I may just skip it and just reuse an old avatar that fits the said season or holiday/event.
Sooner or later I am going to come up with a Halloween avatar when the mood hits me. I usually stick to Halloween-ish colors like black, orange, purple, and green.