So many times when people are trying to learn how to hand sew generally and tailor specifically, they hold the thimble out of the way or use it incorrectly because it is foreign. An old apprentice’s trick is to tie back the thimble finger to the first knuckle with a leather strap or cord. This way your thimble finger is in the right position to support and push the needle.
If you get an open-ended thimble, it is even easier. Here is Wally’s really professional looking version:
Here is a less professional looking once improvised with embroidery thread on a leather thimble:
While we’re here, lets look at the right way to hold a needle when using a thimble: