I've been using featured images for a while and everything seems to be working fine. These images appear on Facebook and Twitter and there is no problem at all.
But one day I decided to try to use the search bar of my own blog. The results were horrible. I was looking for a page that included a featured image, but it was way too big! It didn't fit there, so half of it wasn't even visible (look at the image below).
Now I want to re-upload all my pictures at a correct size, so that they can be featured images, without being way too big or way too small. But...what size should they be?
P.S. I use the Modularity Lite Theme.
P.S.2 I hope you can see this image: http://gunsnwar.wordpress.com/?attachment_id=2336
The blog I need help with is gunsnwar.wordpress.com.