Avoid saving and resaving jpg files. Each time a jpg file is changed and saved it is compressed and you will loss image quality. The preferred option is to save your files as TIF files (or PSD files using Adobe Photoshop software) as they are not compressed and you will retain your image quality. To select your file formats in your image editing software select File/Save as/dropdown menu. If necessary use the jpg format as final file save for smaller files.
Reasons to Shoot JPG.