Julia, if you are using water packed tuna, try oil packed sold white. (Assuming you have no health reasons to avoid oil packed.) in my opinion, it is firmer and more flavorful than water packed. Also gently squeeze it to remove access oil. I find it takes less mayo to moisten the oil packed, so that takes care of some of the access fat calories. I also love my tuna salad sandwiches on toasted bread, which adds texture, but probably isn't good if they aren't freshly made. Do hope you have found some good tips in all the responses.