Well, this is just some friendly advice, Alan. Let me just suggest that you'd probably be better off if you just came straight and asked for leftover or throwaway tracks that people would be willing to donate to you so you can get some practice in, because that's what this is really all about. And there's nothing wrong with that (as long as you and the donor have an agreement as to how you can and cannot use those donated tracks.)
It's when you try and make it sound like you're doing them a favor by mixing their tracks for them for free when you admit that you can't do as good of a job as they can, call yourself "semi-professional", and when you inadvertently mistake mixing and mastering in your spam, that you come off as someone trying to pull a fast one, even though you're not.
Honestly, your post sounds like someone walking into a Just Tires store and asking the service guys if they want you to change their tires for them for free, even though you won't do as good of a job. You'd be better off just asking for a job instead of trying to come off as an independent tire changing specialist.
Just be honest with us and with yourself instead of trying to spam the board, and things will probably go much smoother for you
G.