If you are using removable disk or USB key then you should look at this lesson. I will show you how you can safely remove your device from computer without the fear of losing data.
If you are more of a visual person and would like to organize your folders and files using different colors, than check it out how to use color labels in Mac OS X.
In Gmail there is no insert/upload image option by default. Let me show you how to enable the option so you can upload and insert an image into the email or insert an image by providing url.