Check out this video on how to properly point a stone wall!
It is very important to make sure that you maintain your masonry building structures. One of the best ways of doing so is by making sure it stays properly pointed. When you see mortar joints that are cracking and beginning to fall out, it is time to repoint those areas. This is especially important for keeping moisture from penetrating deep behind the wall and causing more extensive damage. A properly done pointing job can last a long time so make sure the time is taken to get it done properly and preserve you masonry buildings longevity.
Here is a notorious company for pointing tools http://www.wrose.com/.