Remove the seeds from the jalapeño pepper to go easy on the heat.
I do not like onion in my salsa when I am serving it with chips, but if you like it then add 1 finely chopped, medium size red onion.
You can also add 1 clove of garlic, minced for added depth of flavor.
You can store the salsa in the refrigerator, covered, for few days. Though fresh salsa is best in my opinion.