- Use thumbnails or make sure your pic is no more than 600px wide.
- Credit your source if possible. (Ps. "Google" is not a source.)
- If you happen to know where the pic is from (like what magazine, video etc.) you can share that info.
- When quoting posts remove img tags so that pictures you quote won't show in your post.
TinyPic is a good image hosting site. Photobucket has changed their services again so unless you have a paid account don't use it here because they don't allow third party hosting = pics won't show. ImageShack has changed their thumbnail codes, but they provide codes for forums so you can just copy-paste if you use that site.
----------------------------------------------------------------------

From Cancam 2013.01 (credits: blog.naver.com/smile_saku)