I learned Zentangle while I was on vacation in Taiwan this July. My teacher Laura is a CZT (Certified Zentangle Teacher) and she is also a craft store owner in Taiwan. Below is my first Zentangle tile learned in the class.
There are a lot of "tangles" you can learn and draw. For me, each tangle just likes a puzzle, as long as you know the key to resolve the puzzle, then it will be easy to draw the tangle. When you draw these tangles, you will find concentration and peace in your mind. So, it's a very good practice to train your patience and concentration. When we drew these tangles, we used Sakura 01 black pen to draw. Since the nib is very thin, you need to be very careful to control your hand and not to ruin the nib.
Here is another tile I drew after I come back to US. Love it!