Sizing aside, Cali, for the dog shots, I'd suggest getting lower. That change in perspective will yield photos that are more gripping. Don't be afraid to shoot up close and wide for a different kind of portrait as well. As for the photo of your mother, I'd suggest watching your background. If its a strait portrait your after, pick an area of wall which doesn't have any distractions. Aside from that, it's a very well done shot. All told, I think your exposures are bang-on.