The beauty of crystals is there is no right way to choose a crystal!!
But I can give you some tips:
-Reading descriptions and information on what crystals do in terms of healing and seeing which one best suits the changes/help you are seeking.
-Beauty- It is okay to pick them based on just how they look! There could be a reason you find certain stones more beautiful than others.
-Gut feeling- if you just have a weird feeling, or maybe a tingling sensation in your hand when you hold the crystal that could give you an indication this is the stone for you.
-Aversion- This isn’t just simply not liking a stone, this is having maybe a queasy or uncomfortable feeling when seeing/holding a crystal. That could be an indication that you need this stone to help with an aspect of your life.
I definitely recommend checking out more information on these topics because there is a vast amount of it! But I hope this gives you some insight and help if you are just getting to know crystals.