Don't assume he has a condom because if he doesn't, you're both screwed instead of screwing
1. Get up to pee after sex, or you will get a UTI and have no one to blame but yourself. And you will feel so dumb, so dumb, about being that freaking lazy when you're guzzling cranberry juice and searching for over-the-counter remedies to make the pain stop.
2. Always have condoms on you because surprise! Not every guy always has one. I know it seems unfair because he's the one with the penis and god knows women have, like, 4,000 things they need to carry around to look pretty and not get pregnant and blah, blah, blah, and all they have to do is wrap up their junk. Still, none of these arguments are going to save you when you don't have a condom and he doesn't have a condom, so you just sit there next to each other, bitter and horny because now you can't have sex.
3. Actually have the "do you have any STIs" convo before you hook up. It takes so long to learn this and it shouldn't!! I know that it's so much easier to just ignore and hope for the best because it doesn't feel "sexy" to ask if they've been tested when you're already ready to go, but you know what's even less sexy? Having endless panic attacks because you might have all of the STDs, yes, totally all of them, because you risked it and didn't ask him. And now you either have to ask him or go get tested with money you do not have. So just ask before it happens or be safer about it!!
4. Just take your birth control pill at the same time every day. Otherwise, every single time you have sex, you're going to freak out about whether or not you've been on point with taking it for the last 30 days. If you have an alarm set to take it every day at noon, you can screw with carefree abandon, which is the ideal screwing scenario.
5. Realize that lube is not just for old people and is actually really rad. Anyone who has ever had not-that-lubricated sex and wished their body would just cooperate, totally forgetting that lube is a thing and you shouldn't be ashamed that you need it, kind of knows this.
6. Just go get that ingrown hair checked out because worrying that it's All of the STDs is making you slowly lose your mind. If you've ever spent hours upon days freaking out that one little bump was an STD, and praying Google would magically be able to look at it for you and tell you it's not, you know what a colossal waste of time that is. If you can, just go to the doctor so you can spend your time on sitting around and watching TV calmly instead of constantly feeling your own vulva for signs you're dying.
7. Realize that you totally can get an STD from a guy going down on you. Why we don't teach men about cunnilingus and women that they can get STDs from cunnilingus as the primary things we learn in sex ed I will never know. Learning it after you've already had some rando go down on you and being like, "Oh crap," is not the way you want to find out.
8. Don't make out with someone who has a visible cold sore. Two out of three people already have herpes.
9. If his junk smells like a trashcan, suggest shower sex. Or, you know, just suggest he cleans his body because you spent all day waxing yours and the least he could do is make sure his isn't ripe as hell.
10. Realize that douching can actually make you smell worse. Your attempts to make your vagina smell like a garden full of roses and Vanilla Bean candles actually robs it of the good, natural bacteria in there and can make room for bad bacteria, which can make you smell like … well, not that.