1) Make your Custom Report the way you want it with the individuals you want.
2) Click on the Share button at the upper right of the Publish > Custom Report Screen.
3) Select CSV.
4) Select to put data into coloumns (not rows). Usually the default choice.
5) Open the file in Excel.
6) Immediately go to File > Save as and save it in excel format.
7) Review your columns. In some cases, you will want to parse text within a column to separate columns. In some case (like places) that may be rather messy and require some clean-up.