mind mapping is easy. There's a whole bunch of free programms and even apps for chrome that will let you do it to your heart's content. Just google for it!
As for astral travel....
It's easy. It just takes years of preparation to do it for more than a fraction of a second. That includes training to master your mind and to learn how to do lucid dreaming. I doubt you have the gumption to take on the training - even those who believe in astral travelling take YEARS to get to the first plane, and even then, very few of them actually master the travelling part.
SO, your first step: find a master of astral projection, and be ready to not see any results for at least 10 years, maybe even twenty or fifty. You have virtually no chance of learning the techniques without a master to train you and prepare you.