Tip #1: Be in Italy. I know that there is gelato elsewhere and I know that sometimes you're going to indulge because you miss it, but really gelato is best in its homeland. So go. Eat. Enjoy.
Tip #2: If at all possible go to San Gimignano. The gelato there won the world championship. Seriously . It is so good.
Tip #3: Avoid gelato shops that have giant mounds of gelato. If it is piled a foot high in the container it means it's not fresh. Trust me. Don't eat it. There is better out there.
Tip #4: Avoid gelato shops that overly decorate their gelato. The strawberry does not need to be covered in strawberries. If it's good gelato it will stand on its own and doesn't need extra attention.
Tip #5: For flavor go with a cone. The cones provide a lovely crunch and savory flavor to balance out the gelato.
Tip #6: For quantity go with the cup. They tend to have more in them.
Tip #7: Eat it with a spoon. You'll eat slower and enjoy it more. I understand though that sometimes it is just so dang good that you want to shove it in your mouth as fast as possible. Don't feel guilty if you can't hold back.
Tip #8: Try it in hot chocolate. Life changing!
Tip #9: When in doubt Grom it out. If you can't find a local shop that looks appealing Grom is always good and it is in a lot of cities. (They even have one in Malibu. Road trip?)
Tip #10: While in Italy eat whenever you get the chance. You'll miss it. I guarantee.
Tip #11: Don't worry about the weight you'll gain. It is healthier than ice cream after all!
This is what you should look like while eating the right gelato.
I hope this fills you with the joy that can only come from gelato.