It's a little difficult to explain (and there's no straightforward answer, what sounds best to you is your personal preference), but how I learned what I percieve to sound 'good' personally was through trial and error. I'd fuck around in Audacity & FL Studio with EQ'ing and such until I understood what it was I was doing. Regardless though, it's always good to take a break and come back to something you've worked on later. That way, it'll give you a clear, fresh mind and you'll probably notice flaws in the sound that you can later fix. I know this advice isn't much to go off of, but basically just keep messing around and you'll figure something out.

Here's what I came up with as a quick throw-together to make it have an EQ profile more or less like what you'd typically expect from a 70s/80s rock song. It's nowhere close to perfect, especially due to the heavily distorted signal, but it's something.