So, you've managed to get yourself stuck in the Gravity Pit. Congratulations! That's quite the accomplishment.
First things first: don't panic. You'll only make things worse by flailing about like a fish out of water. Or, in your case, a person out of gravity.
Next: assess your situation. Take a good look around. How deep are you? Are you near any obstacles? Can you see any escape routes?
Now that you've done that, it's time for some actual tips. Remember, in the Gravity Pit, time is not on your side. Every second counts, and so do every inch.
Time Dilation Theory: Why Time Flies When You're Falling is a great resource to get you started.
Airborne Self-Awareness: The Secret to Not Losing Your Mind while plummeting towards oblivion.
Don't forget to stay hydrated! Dehydration can cause serious problems, especially when combined with the other problems you're already facing.