If you want animals to understand your letters, write letters that are about 4-5 sentences long. If you don't then they usually say your letters are so confusing. If your letters are good then you will get good presents back.

If you want somebody new to come to your town then make a new town on a different memory card.Then visit one of the towns.(don't forget to use the train and have both memory cards in. Usually the first day somebody moves out of one of the towns and goes to the other one.

Another good tip is to go to the beach and collect the seashells that are worth money. Save your game and come back and usually there is more seashells.

If you want to make friends with the people at the sewing place, talk to them everyday for a while and slowely they will remember you and tell you things about them.