T-bars can be a nightmare, especially if you're new to them. Most issues arise from people being too close to the centre bar.
If you have two people on the T-bar close to the centre then there is next to no space for your boards and you end up tripping over one another as the boards start clattering and crossing over one another. That clattering will often result in a delam of the edge of the board as they keep knocking into each other. Worst case you might fall and get your board hooked on the T-bar. I saw it this summer and it looked real scary for the kid being dragged up the hill by his board.
The easiest way to avoid this scenario is to slide to the end of the bar and hold onto bar in the space you've created.
That way you have as much space as possible between each other and your snowboards. It's simple, but could save you a lot of grief on the hill.
If you're traveling up with a buddy and you happen to have the t-bar behind you, you can still achieve the same result. You can see Sian shifts along the bar and has her spare hand behind her so she still has enough room.