hey there how's it:

I have a cuestion regarding files, I don't know in what format I should manipulate my files like for example if I'm going to import a file should I save it as a tif,gif,jpeg.....etc. and the same goes when exporting.
If you think you can help by giving me the name of a tutorial or an article or explain the basic rules yourself I would really appreciate it.
Thank you very much.