I'll add to this as I remember/think of them. I've got three to start us out with. Feel free to add your own!

1.) Only condition the bottom 2/3 of your hair. If you condition all the way to the roots your hair will look greasy more quickly, and you're more likely to have an itchy scalp/product build up/dandruff. Also, unfiltered coconut oil makes a great deep conditioning treatment! Go all the way to the root and massage it into your scalp. If you happen to have an itchy scalp/product build up/dandruff these suggestions will very likely improve/resolve the issue.

2.) The less you wash your hair the healthier it will be. Dry shampoo between washings can extend this time frame. Embrace the dry shampoo.

3.) Here's one for the ladies:
Seriously guys, you don't want to know.
I've been told by many people over the years that if I tell them that "you don't want to know", you really don't want to know!
Alright, I fucking warned you.
When you wear a tampon, tucking the string inside you helps prevent it from getting gross (from urine, just as one example) so you don't have to change it as often (and we all know how TERRIBLE it feels to pull out a dry tampon), and it keeps the general area and your panties from getting as gross.