It is not so much the machine as the assistance you can get from your store.
Find someone who gives lessons AND have knowledgeable staff.
Stabilizers is more important that the machine by far. Tshirts need a strong backing and the backing needs to be adhered to the inside of the shirt. A top stabilizer is also highly recommended. Use a light weight water soluable on the top and a sturdy cut away on the back. Select a design that does not have too heavy a pattern. That is to say, it should be more of an outline style and less of a full stitch (no background can be seen) design. ALWAYS make a sample on similar fabric.
As you go along and learn your craft, you will be able to venture into more and more designs. Start out simple and progress. You should have good success.