Since Costa Rica is considerably larger than many tropical and Caribbean destinations, getting to your hotel, motel or eco-resort may be a bit more effort than you're accustomed to.
Some hotels offers shuttle service, but this is often limited to those closer to the mjaor airports of San Jose and Liberia. Depending on where you're staying, there are several smaller landing strips that get get you closer (much closer in some cases) to the most exotic and isolated places. Ask your resort what they recommend. Sometimes it's nothing more complicated than them charging you a little more to have you picked up.
The metroplitan areas and popular tourist spots usually have a abundance of cabs which are easy to find or can be called for you with a minimal wait. For the most part, cabbies are their own boss and if you find someone you like, you may want to get a business card or even hire him for the duration of your stay. This is especially a good idea if you find a guy you like who speaks English well. A daily rate is usually around $75-$100 and that includes the gas but you're also responsbile for feeding and putting him up if you're staying more than an hour from his home.
If you're on a really tight budget, Costa Rica does have a bus system, but they can be old, unreliable, off-schedule and crowded...but they are cheap.