Wow, congratulations man! I still vividly remember my first purposely induced lucid dream, and that six years ago!

This means that your first lucid dream is a very large achievement. Good job, keep up the great work!

To prolong a dream, I recommend the dream chaining technique:

1) dream spin when you feel your dream fading

2) remain completely still with eyes closed to contrast the motion of spinning

3) concentrate on leaving your body

This will multiply your lucid dream duration by a factor of five.