Remove seeds
When prepping the tomatoes, you can get rid of the seeds by scooping them out with a spoon. This is easier to do if you cut the tomato in half.
Draining
Drain as much liquid out of your tomatoes as possible before putting them in the bowl. This helps to reduce the overall moisture of the dish, so it doesn't end up runny.
Refrigerate
Keep your tomato mix in the fridge for at least an hour if you can spare the time. This lets it marinate and mellows out any excessive flavors from the garlic clove and other ingredients.