Just starting out myself and we also have the same camera!
I take it you are shooting without the benefit of studio lights as I find the lighting uneven across the different faces. The two girls are burnt out in places. The lady in the centre is the most natural
The background is distracting (a curtain I think) and not that I am an expert, but their body positions are a bit slouched. The girl on the right has her eyes partly closed. And again, I am just starting out but I understand it is important to have sharply focused/defined eyes in portrait shots.
If it helps, I have found some great sources of info available on the web to help you with technique, etc, so have a look yourself if you want to find out more.
Sorry if this seems a little critical, but I hope it helps. And like I said, I am no expert myself!