Vaginal strengthening can be achieved through regular practice of kegel exercises. Although fairly easy to do, I have found that using a tool can help you make the exercises more effective.
A Pussy Strengthening Egg is simply a piece of marble smoothly carved into an egg shape. The idea is to insert it into your yoni and hold onto it as long as you can just using your vaginal muscles. You should be able to "grasp" it with the opening of your pussy and walk around the house with it. Something similar to the one I have is this marble egg.
The Kegelmaster is a tool that works by using resistance. Shaped almost like a vibrator, you insert it into your yoni starting with the lowest resistance and try to squeeze the 2 sides of the tool together. Basically you are building up your pussy muscles by squeezing 2 pieces of plastic together that has a spring in between.
The success of using either weight or resistance training is regular practice! Your pussy muscles are just the same as any other muscles - you wouldn't expect to have tight abs simply by doing sit-ups once a month. Exercising your pussy muscles 3 times a week will give your a tighter pussy that is able to massage and squeeze for extreme pleasure!