Though TAT is very largely based on your imagination, it's quite possible to get creative at it over a period of time. I realised I should work on it after 3 unsuccessful attempts.i followed some techniques for the same which I guess helped me to some extent in my selection.
Whenever I travelled anywhere in the city, I used to look outside the window, state at a scene for 15 sec and then close my eyes and imagine a story. This gave me multiple storylines a few of which I also used in my ssb.
Whenever I was travelling with someone, I asked them to do the same and compared stories to understand different point of views.
I realised I was trying to create problems and then find solutions for a story in every picture. I think it should not be the case. If you see a happy picture, it can be a happy story. (Eg. A picture where 2 people are shaking hands. I made a story of 2 college students having a startup idea. They built on the idea and finally secured their first funding)
Remember that the central character is am ordinary person and not a superhero. So if you see a house on fire in the image, do not say that the hero will go in and save people. Hero is the one who will take help of neighbor's to douse fire. Meanwhile switch off electric supply to house and call fire brigade and ambulance. Going in the lit house is not a practical solution.
Try to encorporate you experience. Whenever I saw someone studying/playing sports, I made stories that revolved around preparing for competitive exams or for a callege sports tournament.
If the opportunity presents, showcase your social and convincing skills. (Eg if the picture shows people arguing, show a character that puts sense into the conversation and ends the argument)
Blank picture- I have always written a story on the spot, I have no comments about it.
Apart from these and many other guidelines, make a habit of writing extensively. You may have a lot of content but if you're not fast enough, you may miss out on the opportunity of expressing yourself.
Keep evaluating stories that you have written. Try to do mock tests on newspaper images or YouTube videos, you will be in a better position.
Keep in mind that the story should reflect your qualities. The decisions that you're central character takes reflects you.
At the end the Funda should be to keep it practical, innovative and creative
Thanks and all the best.
May you touch the sky with glory