What types of meats are you having this problem with? Is it all meat or just very lean meats? The meats in restaurants are often marinated, brined, and aged which will contribute to their tenderness. There are numerous recipes online for brining meat at home, but basically it's just a mixture of salt, sugar, and water that you soak the meat in for a period of time. It will draw more moisture into the meat and change the texture of it a bit. It works particularly well with chicken and pork. I wouldn't really recommend doing it with beef though.