My parents have taken care of this by splitting it up - my dad criticizes me, and my mom congratulates me.
I remember when I was in 5th grade my mom congratulated me for passing kindergarten even though I had the certificate on my wall til I was 8 but I think it is because I tutored kindergarteners that year and yes that how bad our school system is when you have to have 5th graders tutor kindergarteners that are failing kindergarten
With my parents it's the opposite, I wish I had an honest opinion once in a while. My mom says "Oh, you're beautiful no matter what you wear" and I'll be wearing a neon tube top and corduroy pants.
my parents are good about compliments =D