There are a few ways to get free coins for the House of Slots game. The best way is to go to the House of Fun facebook page and collect the free coins that they offer every day. Each day several posts are posted which give you up to 1000 coins each. If you have never gone to the facebook page you can collect around 10,000 coins or more by paging back as long as it will let you continue to get the free coins. Usuallly the coin offer links work for about a week.
The offers also have chances to win more free coins by typing something in the comments. You can get the coins by going into the Facebook Game on your PC or laptop, or on the App on your iPhone or iPad. If you are on a mobile device, when you click the link on the facebook page it will automatically flip to and open the app. Then you will see the message that you won the amount of coins. It is easy to just go back and forth to safari and collect all the free coins you can get.