I should add back - there is not perfect answer here. One of the absolutely best ways to get the game right is to test play it hundreds of times, each time closely observing things you like and don't like, then tweaking the game so that those things you like happen more often. 'Fun' is a hard idea to capture or identify. To that end, also try to have some friends or family try the game out and watch them play it. Notice how they play a bit differently then you would - watching someone play a game for the first time, without any idea how it works can help out a ton.
Ultimately, you can grab a stone from the river and it will be rough. If you polish it enough it may some day be a gem.