How do you adapt a casserole recipe to cook in a slow cooker?

Hi there

I have a recipe for beef in red wine which I have cooked before on the stovetop then oven, but I want to cook it in my slow cooker so I can get it on the go now and leave it and it will be ready for dinner later. It has a lot of liquid in it though and I know that it will still have way too much fluid in when it is finished. How much fluid should you have as a maximum usually in a slow cooker recipe? Thanks.