Whether you're 15 or 95, it is neither too early nor too late to start the study of Srimad Bhagavad Geeta. This has been conclusively established by mahatmas through the ages.
If you're completely new to the Geeta or Hindu philosophy then two places to start would be:
When Pujya Gurudev Swami Chinmayanandaji started teaching the Gita in English in the 1950s, the options for studying the Gita were limited. Today, it's a smorgasbord of choices. There is a Geeta translation and commentary to suit every type of seeker in innumerable languages. In fact, the Geeta is the 2nd most translated book in the world. However, that complicates our study because though many of the Geeta publications have the same source material, interpretations can differ widely. Hence, we need to choose carefully and having chosen, give the Geeta a chance to flower in our hearts.
Once someone boasted to  Pujya Gurudev, "I have been through the Geeta many times." Swamiji retorted instantly, "Yes, but has the Geeta been through you?"
Our study of the Geeta will be more fulfilling provided we keep in mind the following guidelines:
- Books are good, they might even provide answers to questions others have had. They can enrich but will never enlighten.
- You need a Guru to really understand and make the teaching true for you. As Pujya Swami Tejomayanandaji once said, "The book cannot answer your questions, only a Guru can".
- No one can force you to go to a Guru - it is entirely upto you. There are many excellent teachers today, one of them is right for you. You will know it when you meet the Guru. As Pujya Gurudev says, "when the student is ready, the teacher will come".
- Make sure you keep company with other spiritual seekers such as yourself. Please do not underestimate the power of satsang. More on this topic in a separate post.
Among the many books available, my personal favorite is the Holy Geeta by Pujya Swami Chinmayanandaji. Just the introduction is worth the book. An excellent accompanying reference book is the Holy Gita Ready Reference edited by Swami Advayanandaji.
In June 2011, Chinmaya International Foundation announced an online & postal course on the Bhagavad Geeta. Watch out for my posts and enroll if you can.
Enough said. Start now, and above all, enjoy the study of Srimad Bhagavad Geeta!
Hari Om and Namaskaar.