Tactics: I feel it's better to make the suspect come to you and not the other way around. I like them to move from where they are comfortable. Use your car to position yourself between it and the suspect. If the suspect were to attack, he would have to run around or go over a section of your car to get to you. If you can't use your car for whatever reason as an obstacle, remember that distance is your friend.
The initial few moments of your contact are the most important as it sets the tone for the rest of the encounter. Also, keep in mind that suspects are evaluating and assessing you as much as you are them. If you position yourself properly, you are cutting into their available options. Assuming your bad guy hasn't bailed on you upon contact, if you have made a decent approach and positioned yourself properly, the suspect is left with three options.
Be Prepared Strategy: In all calls, a suspect has three basic options: cooperate, fight, or run. Anything else is just a form or combination of any of the three.
Tactics: Knowing his three options in advance gives you the upper hand if you take advantage of it. Being prepared begins way before you ever went on duty that day. Being prepared includes working out regularly, eating healthy, and being consistent in your training.
Training, by the way, must include combatives and controlling techniques. I am not suggesting you train like an Olympic athlete or use weights until you become a knuckle dragger. But, if you graduated a decent police academy, you already know what you need to do because you have already done it to graduate. Don't be that slug who relies on good luck or wishful thinking as a strategy. If the suspect cooperates, it makes it an easier call for you. However, if he fights you, you better know how to fight back. If he runs, you better have a plan.