Indexing in InDesign isn't too difficult, but it does have it's minor frustrations and takes time without efficiencies in place. If you have a pre-developed topic list to work with, it's very helpful, and in this tutorial I outline what I believe to be the most effective and efficient way to enter that topic list into InDesign and then generate page references from it prior to actually generating and placing into your document the actual index.
1) paste your topic list into the end of your document (after all edits and content have been finalized)
2) get that topic list inserted into the formal Index panel's topic list by highlighting the list of words/terms and pressing COMMAND/CONTROL + OPTION/ALT + [ which will input the list into the Topic's alphabetical structure
3) from that list, highlight each word/term, press COMMAND + 7 to open the New Page Number Reference window and select 'add all'

This tutorial is for basic, single-level indexing based on a pre-determined topics list