This is something that I see most artists overlook. The album art is a very important piece to the album as a whole. Without the album art, it is very hard for the album to make sales. Why do I say this? It is because music depends on a great visual representation for fans and prospects to pick up the album and give it a listen.
It is very difficult to sell a compilation without art [unless you are Kanye West and not even think to have radio singles or an album art for your project and still sell millions]. But the reality is you are not Kanye and you are going to need pretty good art in order for your album to sell.
What does it take for you to have great album art? Well that question can be answered multiple ways.
For a start, hire a graphic designer. Your chances are you may not be as experienced to design your own album covers but you have crazy visions on your mind. It is okay to talk to graphic designers and have them design a pretty cool album cover for you. You might have to pay the graphic designer but it will be well worth it once he or she delivers their best work to you.
Another way is to join online groups about graphic design and learn how to design your own album covers. This will save you a lot of money, but your art needs to be on point. You need to draw everyday and practice your art skills in order to make your album cover.
If you are an experienced graphic designer yourself, then make sure to listen back to your music constantly to get ideas for a good album cover. You must make sure your music can be properly represented visually. You can also expand on those endeavors as a graphic designer and offer different things outside your music to build your brand (soft skill).
There are countless ways and possibilities but the real question is, which one will you take?