Fun theme photo size recommendations?

I'm using the bp fun theme on my site. But I notice the photos used in blog posts are awkward on the main page of my site. (http://lifespartknetwork.com). I've looked through theme info, manuals, etc and I can't find anything about photo size recommendations to make the images look better on the main page of the site. Are there any recommendations? Is there specific documentation to using the Fun theme?

Thanks!