This is good general programming advice beyond game development. If you think you need inheritance, you probably will be better off using composition because the general "is-a" rule of thumb is, in my opinion, a bad way to figure out if inheritance is required.

More in this old thread: http://news.ycombinator.com/item?id=1992745

In short, use composition and if inheritance is what you want instead, it will become obvious soon enough.