Rewards to motivate more players to participate in wars
In most clans, you usually have a few people that for whatever reason wont attack even though they are opt into war. maybe it's because the other clan is more coordinated and attacked all at once and now they have a big lead in start and your clan has been demoralized. No one wants to "waste loot" as they put it and the losing loot bonus just isn't enough for them. And if you are an anyone can join clan you may have people in your wars that join to be in your war then leave without attacking. This would be motivation to put in the effort to attack before they leave.
Maybe give an extra bonus for each star earned that the player get right away. In form of extra gold or elixir or dark elixir or even gems. other reward Ideas are an automatic boost for collectors that last for like ten hours or a barracks boost or a free shield for a day. the more stars you get the more or bigger award for each star earned.
It doesn't have to be based on stars either. You can base it on % of destruction (so if you try and only get 49% you still get a little something) That can be a bit more complicated though.
Also, a rewards for good defense to ward off those random players that have their town hall unprotected on their war base.
Just some Ideas to motivate some players to be better team players.