You can't beat compulsive liars with being scrupulous about the truth; they can always come up with new lies to tell each other.

You can convince non-enemies, however. It's not really about the enemies. The real enemies are mostly a lost cause. However, if you've made weak enemies but shouldn't have, or if there are people who are undecided, you can just be straight with them. You often don't need to even address the real enemies directly (though debunking them occasionally is good, lest someone mistake weary non-engagement for a lack of good arguments).

Note, however, that you can also "beat" liars without being scrupulous. You could tell your own little half-truths that are particularly effective at undermining the enemies and/or winning you support. I don't advocate for this, but I note it as a logical possibility. (I also note that on social media pretty much no side of any issue ever manages to be scrupulously honest.)