Get a camera, take lots of pictures of things that you like and then turn the best of them into your creations.
I have been an (award winning) artist and art teacher my whole life and have taught classes across North America and Japan. Years ago when asked this question I would say get a sketch book and a pencil, set up some things that you like(and know) or go outside and find something you like to look at and draw it, then draw them again refining and polishing your concept.
Now a days I say get a digital camera and use it to capture what you see or would like to see. Many people have lots of good ideas, but ideas can be fleeting and unless you train yourself to stop and jot them down they can wander right out of your brain as fast as they can arrive. Having some pics to reference just helps in the process. I now also teach photography and editing for artists along with my fine art classes :-) (maybe I should work up a class for quilters too!)
I'm not saying that you are going to be able to get the 'perfect" shot that can be automatically turned into a painting or quilt painting, I use anywhere from 1 to a dozen ref pics when I am working on a composition but that skill can be developed and can also be made much easier by the use of modern computer technology(photoshop) The creation of a quilt painting will still require some drafting/drawing ability to create the pattern pieces to put it all together (there may be a program out there that can assist that process, and it could be done in PS as well but could be rather tedious, personally I get to a stage where the pencil is much faster)
...and of course your sewing/quilting ability will definitely impact the finished product. The embellishing will be where the true artist shines and takes the fabric into the fine art realm. I try to remember to watch "Quilting Arts" when it comes on our PBS station - I have to smile watching the them using the paint, crayons, stencils etc...I taught all of that over 20 yrs ago when fabric painting was "the rage" and I WAS going to pitch all of it out, now I am rethinking what I should keep LOL!
and a word of warning - finding photos on the internet and using them without permission is a copyright violation unless you use copyright free images or have permission to use the photos from the photographer. I have no idea what the rules are for quilt competitions but for juried art shows Originality begins at "conception of thought" and you must be able to prove that all reference materials are your own which means you cannot use free images or photos taken by anyone but yourself.
sorry to be long winded - hope this give you some ideas where to start
Joann