The first question from every new Instructabler is "what should I write about?"
The simple answer is... anything. If you have enough passion to create a project, then you have the passion to share it. You should preferably publish something original, but with tens of thousands of projects already published here, it's possible that somebody else has already had a go at your idea, even if you thought of it by yourself.
Don't let that put you off. It's quite likely that many people will prefer your style of writing, or find your instructions easier to follow.
You should use an Instructable to...
- Show us what you have made.
- Show us how you made something.
- Show us how to do something (demonstrate a skill, rather than produce an object).
You should not use an Instructable to...
- Show us somebody else's work (if you've found something cool online, start a forum topic).
- Try and sell us something without telling how to make our own.
- Post something inappropriate. "Inappropriate" is a hazy thing to define, but please remember that this site is used in schools. Generally, if you wouldn't show your teacher, don't publish it here.