How to take and edit photography like this? (link provided)?

http://thebananaresident.tumblr.com
This is my tumblr blog, I really admire the photography that I reblog from other bloggers. I want to take my own photos in this style to post to instagram and tumblr, because I have admired it for too long and now I want to do it myself. I already have the app VSCO cam on my iPhone 4 (people often say to use this app, but how do I make the pictures look like the ones on my blog using this app)

Most of them are a little underexposed and a bit desaturated. Also the contrast has been lower and in some photos have a vignette. Keep in mind that these photos are from a DSLR, so you might not get the exact result. Cheers