There are four boxes to check off, to know if you are dressed for biking.

1. Not naked (this one is important)
2. Pants not shredded by chainring (I've had this happen to me)
3. Happy butt: Saddle sore formation under control
4. Clothing not turned sticky and icky by sweat-drenching

If you have these four covered, you're good to go. Everything else is based on personal preference...