first off, they are really quite nice considering they're your first painted minis
getting the kind of nice smooth, fine, edge highlighting you see on the box examples or whatever, really takes a lot of practice to get the hang of...that said, from the look of your edge highlights, I suspect you are either not thinning your paint, or just not thinning it enough...mix some water and/or lahmian medium in with your paint, so that your paint has a consistency more like cooking oil (runny, but not too "watery")...and only get enough on your brush to make it just damp, not wet....that should make it much easier for you to keep control, and get nice smooth, subtle highlights, building up multiple layers to make the colour stronger, rather than one thick, hard line...but in any case, just keep practising and working at it...you're definitely off to a good start