I’m with Karin. Go for .com whenever you can. I would use .net as a last resort. These domain name companies are always coming up with a new suffix so they have more names to sell. I’d do it too if I were them!
I would not think of doing it. I have a hard time remembering .org and .net, and those have been around for years.
If you think of it because your website name idea with the .com suffix is already taken, then you just end up directing traffic to that very site because .com is the default that people use.
While we want our web site names to say something about us, it is even more important that people can remember them.