When I'm working on a complex document such as a long article or a book chapter, I always have to make changes to text I've already written, move text to another position in the document, grab text from another document to insert in the current document, or leave a "hole" in the document until I gather the information I need. I've developed some shortcuts to make my life easier, and I call them my "get-to-the-right-place" tricks.
1. Marking "holes" in documents
Whenever I get to a topic or paragraph that I know has to be included, but I can't write that section yet (I don't yet have the information I need or I have writer's block), I mark that hole so I can get to it later with Microsoft Word's Find feature. The best mark is text that won't exist anywhere except at the hole. I've found that "$$" works best, because I've never used (or seen) two adjacent dollar signs in any document. I enter text as a reminder of the topic (usually a heading or first sentence for the topic), then add $$ to the end of that text. When I want to see where the holes are, I enter $$ in the Find dialog box (Ctrl-F) and move through the document's holes (yes, that's plural, I frequently have multiple holes when beginning a writing assignment).
2. Returning to the last cursor position
For a while I also used my $$ trick to mark the place in the document where I stopped working, so I could return there when I opened the document again. But then I found that Word remembers the last position of my cursor when I save and close a document. In fact, Word remembers the last three positions of my cursor, which is incredibly powerful because it's not limited to a single document.
When I open a document that I'd been previously editing, I press Shift+F5 to move to my last cursor position. Pressing Shift+F5 again takes me to the next-to-last cursor position (where I often find that I want to make more changes).
If I've been working with a "notes on the subject" document, and copy text from that document into my final document, and both documents are open, Shift+F5 moves me (in reverse chronological order) through my last cursor positions between the documents. Because Word keeps tracking my cursor, I can continue to get where I want to be in both documents as I select text in the "notes" document and copy it to the final document.