Tipping - all restaurants add a 10% service fee to the bill automatically. This is supposed to cover the service (like a tip) but in most cases the restaurants simply pay a pittance of a salary to the waiters/waitresses so if you receive exceptional service in a good restaurant there is nothing wrong with leaving a small tip for service above and beyond the call of duty. An extra dollar or two maximum is usually fine. Most non-tourist area restaurants the locals would not expect you to tip.
You might also strongly consider giving a small tip to your guides or tour bus drivers. When you get an exceptional guide who really knows the place you are visiting and just where to find those amazing things you would never find by yourself - just remember most of these guys receive very little salary from the tour operator. It doesn't hurt to drop them a few dollars at the end of your tour.
Currency - The currency used in Costa Rica is the Colón (pronounced the same as cologne). At February 2012 the exchange rate is roughly 510 colones to $1 USD. Best not to bring travelers checks (very long lines at banks). Your best option is credit or debit cards. There are a lot of ATM's scattered around the country and you can get cash when you need it (in dollars or colones in some ATM's).
Driving - drivers in every country have a certain style. Some in Costa Rica drive very aggressively and you may be a bit shocked by the lack of respect for safety or laws. Often motorcycles and taxis will zip in and out of traffic, in some instances driving on the shoulder of the road or straight at oncoming traffic in the opposite lane just to get wherethey are going as fast as possible. Ticos are not bothered by this and neither should you be. Drive defensively and you should be fine.
Roads in many areas of Costa Rica have been improved dramatically. However, since the earthquake in 2005 there are still some roads that are damaged. You will also find that roads can be very rough in remote areas of the country - in some cases only accessible by 4x4. If you plan to rent a car ask the rent-a-car company about roads in the area you plan to drive.
Taxis - always use the red taxis with the distinctive yellow triangle on the door - these are officially licensed Costa Rica taxis, which means their cars must pass inspection and they must carry insurance. There are a lot of "Piratas" (illegal taxis) that will offer you a ride but you never know who you are getting in to the car with and forget about insurance if you have a wreck.
Airport Taxis - at the airport you will see specialized "orange" taxis with their distinctive white wing logo on the door. You purchase the fare from a little booth located in the area just after you clear customs. It's less than $20 to get to San Jose. If for any reason you don't find the booth to purchase the taxi fare you will notice the taxis on your left as you exit the airport.
Buses - Buses are everywhere and they are cheap. Most fares are between 150 to 300 colones (about 30-60 cents US) in and around the San Jose Metro area. Fares to various cities around Costa Rica are very reasonably priced. Check out our Costa Rica bus schedule for more information about when and where to catch a bus to just about anywhere in Costa Rica.
Buying Coffee - if you don't care what you spend there are tons of tourist shops in hotels, resorts and near attractions selling coffee for 2-3 times the price you will pay in a local supermarket. It is difficult to buy a bad brand of coffee in Costa Rica but the super cheap brands are ground too finely for my taste and make the coffee a bit too bitter. Go to the grocery store (such as Mega Super, Mas x Menos or Auto Mercado and look for brands that have labels in English and Spanish to get a more "Export" style of ground coffee. Many are also available in whole bean for the home style Barista.
Phone Cards - most public phones no longer accept coins so if you need to make calls using a pay phone you will have to buy a phone card (tarjeta telefonica). These come in 1,000 or 3,000 colones denominations. If you travel with a small laptop it is worth having a Skype account. Calls from Costa Rica to the US run 2 cents per minute (or free between Skype users).
Street Safety - A North American man I know was walking in downtown San Jose and a young man approached him and said "Hi, how are you? Remember me from the airport" and stretched out his hand to shake hands with my friend. In 2 seconds he nearly had the watch off my friend's wrist but fortunately the plot was foiled (the young man ran away).
In most cases it will be obvious you are a tourist. Be alert and be wary of anyone being overly friendly with you (as you would in any country). Petty theft (including pick-pocketing) is a big problem in major cities such as San Jose and Alajuela - as well as in major tourist towns such as Jaco. Do not walk around at night alone in the city and if you must go out at night stay in well lit areas where there are plenty of people milling about.
NEVER leave anything in plain view in your car. You are asking to have the window broken and things taken. Lock valuables in the trunk or leave them in a hotel safe. A high school educated person in Costa Rica typically makes less than $6,000 per year - better not to tempt anyone with fancy jewelry or by flashing lots of cash.