When you say priming sugar, what priming sugar are you using?
Any fermentable sugar you can get is all you need. Table Sugar, Corn Syrup, Honey, etc. I've just finished up using Agave Nectar that I had to buy a big bottle of to use a few tablespoons for something else.
Some sugars like honey and other sugars with strong flavors will add that to your finished beer. Sometimes good sometimes not so good depending on what your beer is supposed to be.
If you are using the priming dots that are premeasured, then those work, but you don't have as fine a control of how much carbonation you add to your beer. They also up the cost of your beers. Though admittedly not much.
If you use something other than the pre-measured stuff, then use the priming sugar calculators on the various homebrew sites. I recommend you go by weight and not tablespoons or other measures of volume.