Look at that solid piece you gave the funeral long back. It’s time to give life to that dead piece. If the T-shirt is cotton then get your hands ready for some creative juice to flow on that plain surface. The fabric painting observes well on the cotton material well.
So, the first & foremost step to take is to dip your t-shirt in clean water for few hours. Let the water soak fully. Take it out don’t squeeze it just dip twice thrice and put it out to dry.