Teach your dog lots of tricks! You can use them at the park when you want your dog to focus on you. Find the tricks they enjoy doing, and be sure to carry a couple of types of rewards with you on your walks so you can pull out the “high value” treats - or toys - when you need them. See the article on treat value at http://www.onlinedogcoach.com/index/members/view-article/129/training
Select tricks from the alphabetical listing at http://www.onlinedogcoach.com/index/members/view-course/109 Some that are great for walks in the park are circle, bow, figure 8 around your legs, pick a hand, and touch to hand. Pick a hand is especially good because it requires more focus and mental strategy!
Another strategy is the “we won’t go that way when you act like that” move as taught by Victoria Stilwell. You need to make sure there is a lot of room, and no one is walking behind you when you do it. This doesn’t really work on narrow trails.
Basically, when you dog starts taking interest in another dog and starts to pull, whine, or bark, calmly turn around and walk away from the oncoming dog. Reward when your dog does any of the following : looks at you, willingly comes with you, calms down. You can put your dog in a sit or down, and reward that. Use the tricks as mentioned above!
Let us know how this turns out! Post your update here, or in the Success Stories forum at http://www.onlinedogcoach.com/index/forums/viewforum/4/