I use a cunningham hook for the tack, single line
for the clew. We can reef in about a minute or less with my crew. One is lowering the main, while another is pulling in the reefline and cunningham, then tighten up the halyard, loosen the boom lift.
As said, let the main sheet out, have enough tension on the boom so the end is slightly up seems to work best for me any how. We're pretty quick about putting in a reef depending upon the length of the course. Sometimes as pudding mentioned, if a short tack up to the windward mark then down wind, just have someone REALLY working the main sheet during gusts, or leave it pretty loose, then you have a full main for the down wind leg.
Sometimes we do reef on the downwind leg getting to a buoy. not any harder than doing it up wind.
At the end, depends upon the size of the boat and its design. My boat is probably more like puddings personal boat, the Farr he races on will probably go a bit higher winds before a reef is needed. Some boats were never designed for reefs too!
Best thing frankly, practice before needing to, or have a plan on how you want to reef, then do it, if it does not work, figure out what did not work, improve the next time.