1. Gather allies.
...If three of us demonstrate outside a mosque, and five hundred Muslims protest our demonstration, we will look like a small, unpopular fringe group and the Muslims will look like the mainstream majority opinion. This kind of thing has a psychological impact on anyone watching this on television because of the principle of social proof. But if five hundred Muslims demonstrate and ten thousand counterjihadists protest their demonstration, it sends an entirely different message to anyone watching on television or participating in the demonstration. Numbers count.
2. Coordinate efforts.
If there were a hundred thousand active counterjihadists, but each worked on different projects, we wouldn't accomplish much. But if most of us worked on a few central projects, those projects would be much more likely to succeed.
3. Concentrate force at a decisive point.
Many times in history, a military force was outnumbered and yet won the battle. Often it was because the principle of concentration of force does not require absolute superiority in numbers. It only requires a local superiority at a decisive point.
Edmund Burke once wrote, "When bad men combine, the good must associate; else they will fall, one by one, an unpitied sacrifice in a contemptible struggle."
