In GMAIL use INSERT FILES FROM DRIVE for an easy way to share files.
I really like this way to share files because I always have my Gmail open and I'm using it all day so it's easier than having to go to my Google Drive, find the file, and share it from there. I also like to share files this way when I'm sharing with people outside my organization because the email comes from me and has my signature with my contact information. If you share from Google Drive, you can include a message but the email is sent by Google and does not have your email signature. Finally, this method is the best way to share a file again if you have previously shared it with someone. One of my co-workers asked me to share a file with him that I had already shared so I sent him an email and inserted the file from Drive.
