In military strategy (and martial arts in general), there is a common technique for engaging and subduing your enemy. It's called the PrESS technique: Protect, Entice, Seize, and Strike.
Protect means to ensure your defense is up and that you are prepared against any attack against you. This means getting in a defensive stance, making sure you have an exit, guarding your vulnerable points. Entice means to open up a vulnerability or opportunity that draws your enemy to attack you in a specific way.
Seize means to trap your enemy, either by grabbing him, ambushing him, or putting him in a vulnerable position where he is left unguarded. And strike means to hit your enemy at a vulnerable spot that injures him or takes him out.
Although this technique has its root in military strategy and fighting, its application can be used in many different areas of life where you are facing competition, conflict, or struggle. Let's take a look at a simple example.
Let's say you are trying to raise money from donors for your charity. Here's one way to use the PrESS technique:
First, protect yourself against "no" by avoiding making a direct request for donation.
Next, entice your prospective donor by asking her simple requests that she can easily say "yes" to (e.g. writing her name down in support, coming to an event for free, subscribing to emails).
Next, seize the opportunity to connect, interest, and delight your prospect. Bring your prospect into a community, connect her to potential friends. Share your story.
Lastly, strike by asking for a donation, making the payment as painless as possible. Once your prospective donor feels a part of a larger community and feels aligned with your objectives, she will be much more likely to donate.
I could go on and on about how to use this technique. The important thing to keep in mind is that engaging with someone else, especially where you think there is conflict, is a process.
It's not simply a matter of directly arguing or asking them something. It's a matter of opening them up to your ideas. The PrESS technique is one such method for doing this.