Rule: No fouls, unless you have a foul "to give". Certainly no shooting fouls. If you have less than six team fouls, and their star player is making a move to the hoop, you could foul before the shot. Now they will have to reset and pass it inbounds again, taking possibly more time to get off the shot.
If the ball comes up the sideline, rather than batting it out-of-bounds, try to keep it in play so that the clock keeps running. If you must "bat" the ball, bat it into the back-court.
Diagram A shows a zone defense against the full-court long pass. Diagram B shows a zone against the half court throw-in. In this situation, X4 and X5 protect against the long pass to the paint. X2 prevents the pass up the sideline for the corner three-pointer. X1 must cover the 3-point arc including the top of the circle and the weak-side, being wary of any weak-side pass (a skip pass to the left side of the 3-point arc). Also be wary of the inbounds passer O1 stepping inbounds, getting the return pass and the three-point shot.
Of course, if the opponent is down three points, put all four defenders on the three-point arc with hands up. Give them the two pointer. Do not foul the 3-point shooter... it's harder to make the shot.
What about fouling and putting them on the line for two shots, thereby denying the 3-point shot. Some coaches would do that and that may be good stategy if there are only 1 or 2 seconds remaining and the ball is already in their half-court. It's a little risky with more than 3 seconds on the clock because they could make the first shot, miss the second intentionally, get the rebound and score... possibly even a 3-pointer (on a long rebound). So if they make a free-throw and they get a chance for a "3", you could actually lose the game.
When we are up by 3 points with just a few seconds remaining, we will put all five defenders around the 3-point arc, and will not play helpside inside the arc. Too often, a guard will dribble-penetrate and then kick the pass out to the 3-point arc where the helpside defender came from... for the wide-open 3-pointer.
Once the ball goes inside, we try to deny the pass back outside, and will give up the 2-point shot. Defenders on the outside should contest the shot by getting a hand up high (without fouling). We switch all screens on the perimeter to keep pressure on the ball.