dexterity only comes with time as you need to teach your hand muscle multiple new movements. Getting more accurate, fluid and faster all relies on your muscles ability to work together. This is why the key is to practice, practice and practice some more :)
There are unfortunatly no shortcut but the beginner's guide is the best way to start as it will give you those basic, fundamentals exercises to start working those muscle.
I know how frustrating it sometimes get in the first years. Just remember to practice those exercises in every of your practice sessions and you'll see results I'm sure of it. It just takes some time but it's normal, we all had to go throught it.
Let us know how it goes.