As said above.
A small part of my previous career involved doing some work with CorelDraw and PhotoShop, and I also messed about a bit on my own--so count that as several decades of light messing about with graphics software. I've since upped my skills quite a bit, but only because I pushed and tried to do things I didn't yet know how to do, but learned in the process of doing.
The internet is a great tool. When I'm playing around with a design idea, I Google and look for inspiration in terms of composition and drawing style etc. However, too often I find something and think: "This is freaking PERFECT for my design!" ... or near enough anyway, that I am tempted to directly incorporate it into my design rather than merely find inspiration in it. My point being, the WWW leads to laziness.
Yes, sure, I have paid for rights to some photos that I have used in my designs, but I try to avoid that with clip art type stuff, and create that myself.
One way to get better with a design tool is to down load a graphic that you like and put it on one layer, then recreate the graphic on the layer above from scratch. An exercise like this is a great way to push past your current skills and learn new techniques. In any case, realistically you'll need some graphics skills to make use of any graphics you did buy, so best to start working on it.
Beyond the art, there is the subject matter. What niche will you be targeting with your designs? You can't be everything to everybody. Pick niches that you know and understand so you can create designs that connect with your target, all the better if it is an underserved niche beneath the notice of the big players.