Port-Starboard: For novices racers unaccustomed to a crowded start line, this means you should be very cautious if making your final approach on Port Tack. The need for vigilance applies equally and emphatically to both tacks, however, so I recommend designating someone to keep a constant lookout under the jib.
Windward-Leeward: It is quite common for racers to approach the committee boat end of the line on a lazy and comfortable reach, however this leaves them vulnerable to being forced above the line by a right-of-way boat coming up to the line from leeward. If the encounter occurs before reaching the committee boat, the windward boat may in fact be forced to tack away. It is not uncommon for beer can racers, in the give-way windward position, to simply ignore hails from the leeward boat and continue merrily on their way, a blatant transgression known as "barging". Such an error immediately brands one as either ignorant, oblivious, or both.
1) The safest approach I can think of is to plan on arriving at the committee boat end of the line with about 20 sec to spare, and in a position several boat lengths below the line. This gives you both a margin of error on your final approach and time to play with if needed, and also room to head up in order to yield to a leeward boat if needed.
2) A more demanding yet more flexible approach consists of sailing down the line from the pin end on port tack, a few boat lengths below the line, with about 60 sec to go. Starboard tack boats have already committed themselves, so you simply look for an open space and tack into it.
This demands a little more confidence and boat handling skill than the previous approach, but if the line is long and the fleet not too large it works quite well. Not recommended on crowded lines, however, as the chain of starboard boats may possibly be bow-to-stern with no openings. In such an instance an experienced racer can still pull it off, however, by tacking early and well to leeward, giving themselves both the time and space needed to come back up to speed and then force their way in by pushing a windward boat up above the line.
Don't waste your time milling around aimlessly during the 5 min countdown. Know where you want to be, and when, to make your last tack and begin the final approach. This means already having a clear idea about your strategy.
I recommend redundant timekeeping: both skipper and one crew member, the later serving as a backup if the skipper has trouble. In my opinion a watch with an automatic repeatable countdown function is a must. If you are participating in a large event with many fleets, all you need do is set your countdown at 5 min and synchronize with a preceding start, and you're all set when it's your turn. Casio has such a watch and it can be found at about 25$ online. Surprisingly, many of the higher end watches lack this important feature.
In over two decades of S-22 racing, I've only known of two instances when a tuna was so badly damaged as to be declared a total loss. This did not happen during actual racing, it did not happen during the start sequence, rather, it occurred pointlessly and avoidably during the lazy back-and-forth sailing below the line that so many boats engage in while waiting for their turn in the starting order. This is a DANGEROUS PLACE! It is very crowded, and too many people have not yet shifted into the state of vigilance needed when actually racing. Where then should you be?
Stay above and outside the line, that is, beyond either end of the line, and to windward of the crowd going back-and-forth beneath the line. Here you have three advantages:
1) Safety. These areas are far less crowded.
2) You are guaranteed not to be caught too far downwind of the line, unable to make it back up in time, when your sequence begins.
3) It is an excellent vantage point from which to view earlier starts, something that can yield important information as you gain experience and learn what to look for.