When it comes to self defense, your best option is often to train in combat sports where you will have sparring matches with a fully resisting training partner and you will be putting yourself in advantageous positions (Takedown, mount, back control). Wrestling, Judo, Brazilian Jiu-Jitsu come to mind as viable options.
In this video Professor Ricardo Almeida demonstrates a few simple takedowns used against common strikes such as the Roundhouse Kick, Overhand Punch, Thai Clinch, Push Kick and even a Collar/Shirt Grab.