I'm beginning work on the sequel to "An Amazon Scorned". (The working title for this sequel is "Amazons' Most Wanted".)
It takes some time, but outlining the chapters is well worth the effort. It doesn't have to be detailed; just a sentence or two about what's going to happen in each chapter.
I prefer to do an outline one of two ways. Either:
1. Use a Word document, or
2. Use index cards.
These two methods work well, because if you realize you've forgotten a chapter, you can just add it as an index card or another line in the Word document. If you write it out on a page, you'll either have to use pencil and be prepared to erase a lot, or to use pen and a fair number of arrows to show added chapters.
If you're able to write out the chapter list from beginning to end without any hesitation or mistakes, more power to you... this is just what works best for me.
Since this post is about planning, here's a bookend prompt on the wisdom of planning ahead. I've given you the beginning and the end... the middle is up to you. Have fun, and keep writing!
Left Bookend: He double-checked the building plans. The last thing he needed was to get caught in a corridor when the alarms inevitably sounded...
Right Bookend: He finally stopped running a few blocks away. Doubled over and panting, he started laughing uncontrollably, relieved and grateful that he'd managed to get away.