on Writing Helping Writers:

Writers who don’t outline are often very loud online. They will say outlines kills creativity. They may even go so far as to claim an outline is a ‘straightjacket’ and that writers who use them are ‘less interesting’.

The case for outlines …

It’s faster. If you use an outline, you’re much more likely to finish your novel in months (sometimes weeks!), than years. This will also enable you to write more.
You won’t get lost. Lots of writers end up blocked and frustrated when drafting without an outline. This in turn gives you confidence.
You’re less likely to screw up. Writing is hard, which means we can end up writing ‘the wrong stuff’ (whatever that means). Far better to write the wrong stuff in an outline than write many thousands of words you then have to cut altogether or pick apart.
Outline = smoother draft generally. Outlines allow you to explore stuff like tropes, genre conventions, storyworld and other thematic elements upfront. This means writers can see what works and what doesn’t, tweaking and refining. So far from being a ‘straightjacket’ or ‘killing creativity’, it actively ADDS to it.

The thing with the outline is you can do it any way you want. Really! It can be as detailed or as loose as you like. You can create your outline using software; you can draw it by hand, or you can use Post-It notes or index cards … or a combo of all of these! Check out these tips for more outline approaches … good luck!