Trial and error has been the operative term. I haven't found it easy to grow tomatoes one block from the ocean even though this is Southern California. We aren't gifted with warm sunny summers; rather, I find myself using the terms foggy, cold, gloomy, and chilly to describe most of the day. In fact, if you do come to Southern California to visit the beach in June, be prepared to freeze during your attempt to sunbathe on the sand. You may even get a burn; those UV rays are pretty good at cutting through the fog and clouds.
Number one: I follow the advice of this goddess of tomatoes. Yes, I do add all those ingredients she suggests when I can and I do try. Yes, yes, and yes to the bone meal, aspirin, eggshells and so on.
Number two: I think it's critical to pick the tomato variety best suited for your climate. For my little garden spot one block the ocean, I've found the smartest way to go is to buy cool climate varieties. How do I find out which ones are cool climate tomatoes? Easy. I check out this guy's site.