Step1
Plan to Perfection. Establish goals, the motivations for those goals, and the manner in which you will achieve them. Be thorough, but also flexible. Too rigid a game plan, and it's difficult to adapt to change; too loose a plan, and it's easy to flail under stress.
Step2
Engage. To really "wow" the woman you desire, you must establish a rapport. At first, it is best to go about this in a friendly manner; be the good guy. Be interested. Actively listen as opposed to waiting for moments of silence.
After this, it's best to move from friendly emotional contact to a more desire-driven attitude. Make comments about appearance. Use light, appropriate touching (especially of the hands, arms, and waist).
After you've established a relationship with your desired partner, and have made it clear through words and actions you're desire for that person, it's time to take action.
Step3
Once you and your partner have made the decision to engage in the "Other Guy" type of relationship, it's best to establish rules, habits, and escape plans.
Rules refer to the level of the relationship, whether it be purely physical, emotional, or some combination of the two. At this phase, it is also important to establish boundaries and run through "what-if" scenarios (WHAT IF we get caught, WHAT IF the other relationship ends, etc).
Habits are very important in this type of relationship, because they are the key for the "First Guy" to see the problem. Habits should be avoided at all cost. It is best to fit in the "Other Guy" relationship in schedule holes already existing in each other's lives. Avoid regular contact; all meetings should be purely irregular, yet not random. Avoid areas where mutual relations are known to be.
Finally, there is the matter of Escape Plans. Similar to the "What If" scenarios of the Rules, Escape Plans refer to the ending of the relationship, the avoidance of altercation between "First Guy" and "Other Guy" and the general dissolution of contact. As stated in the previous steps and rules, this is an area which demands the most planning, and requires the most calm and confidence. With proper planning, though, everything should go off without a hitch.