You can both "win" or both "lose" if your goals are not in direct conflict (rare).

I'd argue that the most important thing when trying to win wars is to aim for realistic outcomes.

The first gulf war was arguably a win because of realistic goals (get Iraq out of Kuwait and stop them from invading it again), while most other interventions in the region were basically "designed to fail", and unsurprisingly never achieved anything of note (and the problem was not lack of military capability).