your landscapes definitely are beautiful - i love that! for those bits of digital, are you using ms paint? it looks like ms paint. props to you on this cover, it looks very good, especially with such a limiting program, but im not sure the comic icon looks equally good. if you are using ms paint, look at some youtube tutorials about painting in it, because some people who use ms paint are bloody genius.
also, im not sure how i feel about your lettering. it needs to be sharper, and maybe download a different font - it looks like youre using a computer default font for some parts, which puts people off. find something individual to your comic - blambot and dafont are good places to look. the 'thoughts' font is good though, just again, make the image sharper.
also, id say looking into the concept of gesture / movement would help you greatly, especially in drawing people. proko has some really helpful videos on youtube. the concept can also be transferred to landscape drawing and help create really nice compositions.
this looks really good, though! you show a lot of artistic promise, and its nice to see someone who loves drawing backgrounds.