One of the best ways to edit a photo on a mobile device is by using PicLab.
They have 3 different versions. PicLab, PicLab HD and VidLab. For advance editing, I use PicLab HD. I’ve been using the app since it first came out and it gets better and better with each update.
For this image, I used Camera+ to take the picture and to apply a filter. I then used PicLab HD for the creative and finally used Instasize to scale the picture for my Instagram.