It can be very difficult to correct poor writing habits learned before the child starts school. It's very important to make sure that the child is holding the pencil correctly and you need to remember that letters and numbers never begin at the bottom. Don't just look at the finished writing, watch how the child forms the letters. Where I come from we teach lower case letters before introducing capital letters and we don't like to see a child write his/her name entirely in capital letters. Confusing b/d, and 6/9/p is common. You just have to keep working at it, but correct formation helps. Do a Google search, there are lots of helpful handwriting websites.