Our data warehouse got a compression ratio of 68% using page compression. The best compression ratios are usually with star schemas with all (or close to all) integer surrogate keys. However, beware of compression's effect on data loading time. If you already are squeezing your data load into a small window of time or if your data load is CPU bound, you MAY be in for a surprise.
See The Data Loading Performance Guide for how compression affects CPU usage/data loading time and much, much more. It was created for SQL Server 2008, but it remains relevant today.