For Indie authors, one of the biggest obstacles to attract reader attention is the cover. Hiring a good cover designer is expensive (although I absolutely recommend it), but getting someone unexperienced will cost sales. Despite the saying, people do judge a book by the cover.
Since I'm not exactly rich, I have been doing the covers for my books myself and learned by looking at other people's covers. I was never satisfied with the results. Therefore, I spend some of my hard earned money on a cover design course by WMG publishing (owner is Indie author guru Dean Wesley Smith), and it was brilliant.
I learned so much in such a short time (the courses are mostly 6 weeks long). We covered everything from the basics to branding, and although I'm not someone who can afford InDesign, using my ancient but faithful Photoshop 7 and the free GIMP program worked well for me.
I highly recommend this workshop if you plan on doing your own covers. It is money well spent.