I like to use the first two lessons of the semester as introductory lessons. The lesson usually begins with me telling the students about myself, where I come from, hobbies, interests, etc. Then I turn the lesson over to the kids and get them speaking about themselves. It's usually difficult for them to come up with the right words so I like to provide them with a worksheet which acts as a guideline for their introduction.
One option is to get them to interview each other using the worksheet on the right and then ask the students to introduce their classmates. Or you can opt for the "traditional" route and ask them to introduce themselves using the worksheet below.
Note: This can be adapted to fit the 4 basic learning areas of ESL, i.e: Speaking, Reading, Writing and Listening.