With online dating you don't have the pressure of the introduction or the awkwardness of a blind date.
You can communicate with as many or as few members as you like and by the time you decide to meet someone in person, you will already have a connection with them and the excitement to see if it will go further.
Some dating sites are for casual encounters or companionship, some cater to singles that may have moved to a new place and are looking for new friends, some are for individuals from a particular background or religion, while others are for singles looking to find "the one". It helps to figure out what you are looking for in your relationship.
In addition, many sites offer free trials, or the ability to view matches for free.
It is only when you want to communicate with your matches or use more features, that you must signup for one of their membership plans.
In addition to these "icebreakers", you can communicate via email or chat/IM, or even through a webcam conversation.
Some sites allow you to call each other on the phone without revealing your actual phone number.