This is some advice fron an instructor I took a hand applique class from a few years ago, and her tips work for me. I use a needle called a straw needle or a milliner's needle. They are longer and seem to give me much more control. Also, use a fine weight thread. Her favorite was silk thread. I've also used a polyester thread called So Fine and it works pretty well. For small pieces, she told us to put a dab of glue stick on the back of the piece to help hold it in place instead of using pins.
Hang in there, because this is a skill that takes time.