There are three main areas to focus on when trying to speed up your metabolism; hydration, regular eating, and sleep.
Drink at least half your body weight in pounds in ounces. So if you weigh 150 pounds you need to drink 75 ounces of water.
Eat every 2-4 hours, and include protein at every meal and snack. Eating every couple of hours keeps your body digesting, which is burning calories. Eating protein helps to maintain muscles, plus protein takes more energy for your body to digest. It is a win-win.
Sleep at least 7 hours per night. Some people need more but getting a consistent amount of sleep every night allows your body to regulate hormone levels, and build and repair muscles. Regulated hormones and strong muscles keep your overall body system functioning at peak.