I have 2 bikes to choose from. On Monday and Wed/Thurs, I use my beater bike that has pannier attached. Take my clean/ dirty clothes to and from work. The other days, I ride my road bike and not carry anything except water and ID. If I ride my road bike and need to carry stuff, I have a deuter backpack which has a mash back to keep your back cool.

At work, I use baby wipes also. And I've cut my hair to a pixie style so it's really easy to style and not have to worry about helmet hair anymore.