The basic idea is to use transfers in order to give the overcaller a chance to bid twice with very good hands. Both majors 2 Transfer to hearts 2 Transfer to spades 2 Spades and a minor 2NT Hearts and a minor 3 Natural 3 Natural 3 Natural, preemptive 3 Natural, preemptive Note that initial actions are sound overcalls.
Most overcalls are something that resembles a decent opening bid with some playing strength.
This means that we might get shut out with 13 vs. 13, but since it is quite possible that we have a game, we can't afford to bid light and get doubled at the 3-level after a game try. After an initial double, some play system on, some play natural. In either case, I suggest making a 2 response to the double be a scramble, not showing much of anything, just usually fear. It might be a reasonable shapely hand that doesn't want to play 1NT doubled and doesn't have a convenient way out, but that's rare. A redouble of 2 is takeout.