I use the eraser almost as much as the brush. If I see any bumps or edges sticking out of the strokes, I either make the line thicker to cover it up or erase them. If I want some help with longer lines, I use the pencil tool to either stroke the paths, or to make the paths into selections which I then use to delete stuff within it.
Since you don't have a tablet, getting some smoother strokes is a hassle so I'm afraid I have no advice to offer on that end. I try to make the lines look good as I'm drawing it, but there's plenty of options to modify it afterwards so that it looks smooth and fine. And as I've been telling others, having the same thickness on all strokes usually doesn't look as vibrant as it could be, but if things like body outlines get thick lines while details and smaller features can have thinner lines, it tends to look more alive.
Yo man, sorry to bother you but i was just wondering if you could give me some tips on getting clean lineart? One thing I've noticed in all of your work is how polished it is, are there any techniques/settings you use to get those results?