This is my first planted tank. Any suggestions?
I am not good at art or anything involving design or aesthetics but I have recently done some research on some of the design terms that get thrown around by people in regards to aquascaping. I will take a stab at explaining the basic ideas to you and then you can follow some links to get detailed information from people with actual knowledge and talent about design.
There are methods and tricks (using certain perspectives, manipulating focal points, etc.) that allow the artist or designer to sort of force a certain viewing experience that humans tend to find aesthetically pleasing.
With aquascaping the primary goal seems to be upon using specifically located focal points to not only draw in the viewer's eye but also to help tie together the aquascape as a whole.
The most commonly used and discussed system for doing this is called 'The Golden Ratio.'
Here is a link to an explanation of how to use the Golden Ratio in an aquascape and it just so happens to use a 20 gallon high tank (very similar dimensions to your 17G tank) as the example so you can basically just copy the focal points and measurements to get you started and then fine tune your positioning from that point on.
Here is a link to a general Iwagumi aquascaping article that includes some more info about the Golden Ratio -
Cliff Notes: you need to have one primary focal point in this aquascape and you do not want it to be dead center in the tank - you want it to be off center. In your tank it should measure in 15" from one side of the tank (leaving ~9" to the opposite side of the tank).