Meathooks are pretty advanced, which means there are a ton of things you can do to work up to them, depending on where you're at now.
Single-arm pulling and grip strength is one of the most important elements for a good meathook (even though your arm is straight in a meathook, it's still a pulling movement). This pull-up tutorial has some great advice for building pulling strength. If you're ready for it, you can start working on some of these progressions as single-arm movements. This will strengthen the muscles you'll need for advanced single-arm hangs.
Transitioning into the meathook position and switching to the opposite side requires front lever strength. This tutorial will help you build the strength and control you'll need in your front lever.