Puppy park etiquette

Me and my 4 month old Loki love hitting the local parks. But he gets so excited at the site of another dog that there is no breaking thru. Does anyone have any good training drills?

Also what is the best etiquette to introduce my new pooch to another dog at the park? My typical first step is the simple question "Is he/she friendly?". This usually tips off the owner that I would like to let my dog near their dog.