There are a few things to keep in mind while writing your tips.
First, keep in mind that although challenges might show up together today, that doesn't mean that they'll show up on another day. Avoid writing a tip that references another challenge, because the next time that challenge shows up, it might not be accompanied by the referenced challenge.
Try to give general advice, avoid giving personal experiences. Stay away from phrases like "I think...", and "In my experience..."
Try to avoid double-posting the same advice that as another user. There's no reason to have two tips for the same challenge both telling you to play Gruntpocalypse, for example.
Currently there is no language filter in place, but that doesn't mean that I can't add one. Keep it clean, this site is here for everyone to enjoy. Breaking this rule will have consequences.