To get ideas about good books your teen-agers would like:

* Books and the Teenage Reader by G. Robert Carlsen (Harper & Row) -- An overview of teen reading habits, why and what they read.

* Choosing Books for Children by Betsy Hearne (hardcover, Delacorte; paperback, Dell) -- Sensitive delineation of what parents want their children of all ages to get out of books, basic guidelines for selections, recommendations and synopses of more than 100 titles.

* Now Upon a Time: A Contemporary View of Children's Literature by Myra Pollack Sadker and David Miller Sadker (Harper & Row) -- Comprehensive analysis of what's available for all age groups of children.

* Bequest of Wings by Annis Duff (Viking)--Inspiring story of one family's adventures with books.

Among other hints for parents wanting to entice their teen-agers into reading, gleaned from various experts:

* Don't assume your child's English teacher is up on the modern teen novel.

* Remember that most books for teens are available in paperback.

* Don't get hung up on numbers on the copyright page of many paperbacks, in which the publisher includes a suggested reading level (RL 7, for instance, refers to seventh grade) and intellectual level (IL 8 refers to eighth grade). Teens can become voracious readers, gobbling up anything that intrigues them from fourth-grade level up to adult. Junior high can be a chance for a child to catch up on some of the earlier books missed.

* If your child likes a particular book, get more by the same author.