That's fine, it's the end result that matters. Even if you'll end up with a clear white background it can help during your painting to use a bit darker one. You already got the good colours on there, just vary it like you've done. I never, personally, use smudge or so, but I guess that's from person to person. I have to go to bed now I'm afraid but I'll help you or at least discuss it any way I can. I'll check this thread out tomorrow again.