* Make sure you know what your car rental quote actually is. Liability insurance is required by the CR government, and there is no way around it. Some car rental companies don't include this in the quote, and it's a surprise when you show up. Also, you can waive CDW insurance with lots of major credit cards, like AMEX, etc. but you have to usually bring the paperwork that shows what is covered, or else they'll high-pressure you into buying CDW through them. (I highly recommend Adobe, up front pricing, save me like 15% over the competitor, free SIM card for my phone, free surf racks, etc.)

* Download Google Maps (or Waze) of the entire country, ahead of time. With that done, you can use it to navigate even with your phone is "airplane mode", since GPS on your phone is independent of phone signal. You can also get a SIM card for a CR phone number, very, very easily for like 2,000C (or free) at a lot of car rental places as noted above. I used Kolbi, and it was great, 4gig data for like 12,000C, lasted 2 weeks. You can top up cell phone accounts at most small stores (pulperias), they'll have a sign outside that says "Recargas de Kolbi aqua", or whatever company you use.

* Don't drive at night. Just don't. Animals on the road, people walking on the side, areas with no reflective paint, areas with no shoulder. Not to mention the crazy windy road and weather that can change rapidly from climate to climate as you cross the mountains.

* At restaurants, you have to ask for the check, or you will be sitting for hours. Most restaurants already include taxes and 10% service fee when you pay, so tipping isn't expected, but appreciated. Order a lot of "batidos" (shakes) and "jugos naturals" (natural juices)... Piña, Guanabana, Mora, Caz. Try out "salsa lisano" on everything, buy a lot of "Trits" ice cream sandwiches at the grocery stores, and tons of different fruits.

* Take the antigen covid test, rather than the PCR one, to get back into the US. Cheaper, ours were about $50 apiece, as opposed to $120+

Happy to answer any questions, was there as a missionary 92-94, and have spent a lot of months there with my family, on 8-9 different trips, all over the country. Got back last night from 2 weeks in the Southern Pacific area, around Dominical.