Getting a wakeshaper can help clean up the wake coming off of a boat. If your wake is washed out, consider getting a wakeshaper to clean it up.
Ballast is important for creating a substantial wake. In general, the more your boat weighs, the more water it displaces. The more water it displaces, the bigger the wake.
The most popular way to add ballast to your boat for wake surfing is to use what is known as ballast bags. You put these bags in your boat and then fill them with water.