I'm just not cut out for Central America. It's like Monica in that Friends episode in the Bahamas. Let me spell the horror out for you and establish credibility before I delve into the do's and don'ts.
This is my hair after not washing it for a week. Suffice it to say, I had a really, really, really tough time until about 2006/2007, at which point flat irons got way better and I got more clued into the "being pretty" process. I've gotten it down to an art now, but it involves scheduling my showers (always at night), never blow drying, and having decent conditioner on hand. It's a very delicate process and I looove my hair, but it took a while to get there.
On top of this giant hair situation, I'm really, really, really pale (err, fair-skinned), and I can get pretty sweaty in the humidity. My acclamation to the temps of 'Nam has quite apparently disappeared.
All of this is to say...I was a shitshow in Costa Rica. My hair was Donald Trump yuuuuuuuge, even my shins glowed, every bugbite was like a red polka dot, and I was more than ill-prepared. If I could do it over, I would (I was meeting my coworkers for the first time. Cue Tony the Tiger, only sarcastically).
And if I could, here's how I would.
1. Pack your own decent shampoo and conditioner.
Normally this is something I would probably do. Probably. Again, I wash my hair once a week or so, and if you're anything like me, you understand that this isn't normally a huge issue if you forget. Unfortunately, I did, and the hotel we stayed in had "shampoo and conditioner" (in one — your first red flag) that mysteriously looked exactly the same as the body wash. Ugh. I need something creamy, damnit! It was probably generic brand dish soap, and yet I still put it in my hair out of desperation. It didn't work. A much safer bet is bringing your own.
2. Bring your goddamn comb.
I had this packed, used it, and didn't repack it. God. Finger combing your hair when it's at Amy Winehouse beehive level will either reduce you to anger, near-tears, or rid you of what few fucks you had left to give. So just pack one and put it next to your passport. It's that important.
Also, for those of you straight-haired clueless folks, a brush is not an option. Don't even...don't even joke. It's not funny. Brushes are the devil. What's more, no, a comb isn't a necessary staple. I can go fairly long stretches without needing one, and most other continents would've been fine.
3. WEAR ALL THE BUG SPRAY. All of it. Don't share with others.
Seriously. I'm still scratching.
4. Headbands, bobby pins — whatever you use to tame that shit, pack more than necessary.
Also, if you're really gung-ho, take a day when your hair is a frizzy mess and try to make it look cute. Learn how to make sweet braids or something. I don't know. Or just give up. One of the two.
5. Leave your hair straightener at home.
You're not gonna need it. You might tell yourself you'll need it, but you don't. Also, I know you're paranoid about losing it and/or it breaking, so don't even risk it. Side note: I once had a nightmare that I lost it, and it was one of the more terrifying dreams I've ever had. I say this because if you know me at all, I'm really not into vanity. I hate selfies, I know shit about make-up — that's how serious an issue this is, kids. Not a laughing matter. Don't judge.
6. If you can, try not to wash your hair.
I made the mistake of thinking wet hair would look better than frizzy hair, but then I was tasked with trying to keep my hair wet for the next 144 hours. For the record, I failed. I wish I could've just resisted the frizzy urge and let the natural oils do their work...but I didn't. Don't be like me. Unless you have to, try to duke it out, per usual.
7. Pack twice as many clothes as you need.
Even the non-sweaty girls were rolling through clothes like it was their job. You'll want a solid two outfits a day (potentially three, depending on your activities), not including PJs. Think sports bras, regular bras, tank tops, whatever you have that's loose and cotton-y — the basics. Even if you don't "need" them, it'll feel nice to have a fresh tank to change into.
8. Beachwear is a thing you should get into.
Oh, god. The flowier (not to be confused with flowerier) the better. The less you need to sweat, the more comfortable (and less awkward) you'll feel. Case in point: I was wearing a tank and some yoga capris (way too heavy. Not recommended). My legs were glistening from a day at the nature reserve, hiking, walking, ziplining, etc. At one point, I walked into a wall of tiny little black gnats, and dozens of them clung to my shins. Everyone else got away scot free, and it was either because they avoided the bugs (which would be very impressive), or because they're just not as adhesive as my shiny shins were (far more likely). Sigh. I had to wash my legs off with the water in my water bottle (instead of drinking it, which would've been awesome). I would've been better off hiking in tennis shoes (Chacos?) and a swimsuit cover-up. F'real.
9. Scrunch gel. Probably.
It might be worth it to pretend it's 2005 again and just rock the scrunchy, hard, wet look 24/7. It's not super cooperative and you'll feel pressured to shower all the time, but you'll want to shower all the time anyway, and at least you won't break all your hair ties trying to put your hair up into a ponytail.
10. Cross your fingers.
And take your next vacation in Iceland.