Character sketches: Names, brief background, defining features, quirks. Add to them as you go and come upon them. Helps if you can't remember which person had shoulder length brown hair and which one had cropped black, etc, or which person chews their nails when something is going wrong. Handy and helps you keep it all straight. :)
Treat your locations as characters too. If you're making up your setting, write as much as you can about each place. Names, pronunciations, part of the world, weather, types of trees/plants/buildings/peo
For "outline", unless you have a very clear idea of what you're doing already, don't go straight to it. Start with a synopsis. Break it into three parts:
Beginning, middle, end.
Then expand on that. What happens in the beginning? What happens in the middle? What happens to resolve everything in the end?
Then expand on THAT. What has to happen to make the beginning go that way? And the middle? And the end?
When you've planned it that far, you should be able to get it into something of an outline form.
But the big thing is to write it down. Save it in more than one place, just in case. Print it out if you must. Write it into a spreadsheet if that will help you see it.
But plan. I've done it both ways, and planning is by far easier in the end than just running with it. If you get stuck, you look at your outline/synopsis/spreadshe
Good luck!! :)