Reddit reviews Passing the Guard: Brazilian Jiu-Jitsu Details and Techniques, Vol. 1

From inside someone's guard, passing is really the only viable strategy. If you're up against a skilled opponent, and you try to choke or attack their arms from inside their guard, they can push you away and keep you off balance with their hips. Focus on getting around him. The advantage of an open guard is that it's dynamic, makes it easy to move, and makes attacking faster with less telegraphing. The disadvantage is that it's easier to pass.

There's a book out there called Passing the Guard that I would recommend highly - it really digs into the theory and strategy. Pick a couple simple, straightforward techniques and drill them until they become a reflex. If you can keep steady psychological pressure on your opponent with constant passing attempts, you'll distract them from being able to attack.

Quick note on leg locks as an attack: they're great if they're legal where you're at, but always keep in mind the position before submission hierarchy. If you miss a leg lock, your opponent can often reverse you and end up in a pin. If you focus on dominant position first, and pass to land a pin or mount, you can go for multiple attacks with more control, all while making your opponent work just to get their next breath.