Having trouble coming up with something to draw? No worries - while you'll eventually learn how to start from a tiny seed of a thought and gradually nurture it into a complex concept to explore through design and illustration, it's perfectly fine not to be there just yet.
For now though, here's an idea that might interest you.
In many stories, gardens are portrayed as peaceful and serene places, filled with beautiful flowers and singing birds. But what if a garden was something more? What if it was a secret hideout, a place of adventure and discovery? Consider a garden that is full of hidden paths, rooms, and treasures, with much to explore and stumble upon.
Design a secret room, or chamber, that fits into a garden aesthetic. You can invent the means by which it remains secret, or delve into how such an environment might appear. Or, you might illustrate characters exploring and uncovering its secrets.
Pentel Pocket Brush Pen
This is a remarkable little pen. Technically speaking, any brush pen of reasonable quality will do, but I'm especially fond of this one. It's incredibly difficult to draw with (especially at first) due to how much your stroke varies based on how much pressure you apply, and how you use it - but at the same time despite this frustration, it's also incredibly fun.
Moreover, due to the challenge of its use, it teaches you a lot about the nuances of one's stroke. These are the kinds of skills that one can carry over to standard felt tip pens, as well as to digital media. Really great for doodling and just enjoying yourself.