On the morning of the race, you will check the local forecast again to see how the predicted weather has changed or whether it is behaving as has been forecast.
Get out on the course at least 60 minutes before the posted start time and sail as much of the first beat as you can, making mental notes of the wind patterns to establish which side of the course appears favoured and whether the wind shifts are oscillating or persistent.
Compare what you are seeing with what has been predicted and start to make your plan for the first windward leg, the main advantage of doing this is that if immediately after the start something changes, you will have the information to make a snap decision about whether to continue standing on or whether to tack.
Whilst sailing the first leg prior to the start you can establish whether your setting for the rig, sails and sheeting positions are correct (these would have been set initially prior to leaving the beach based on information available at that time)
Check that the current at different points on the racecourse matches with what you know about this venue from previous regattas or local knowledge research.
Even the best sailors benefit from lining up against another competitor prior to the start and many of us have a tuning partner but if you are at a regatta and your regular mate is not there, work out who might be beneficial to work with and approach them about the possibility.
So many questions can be answered by positioning your boat two lengths from a competitor and speed testing. These tests can and should be lined up in advance with a reliable competitor whose speed and abilities are known and someone you know will show up on time at the designated spot.
Almost always prioritize tactical and boatspeed research over boat-handling practice, you are not likely to solve bigger boat-handling issues in the short period of time that is available to you.
Finally, allow an 8 to 10 minute chill period before the start, and during this time discuss the upcoming race in a low-stress manner giving the team an opportunity to re-evaluate sail selection, and then to fuel up and hydrate.
You are now ready to tackle any eventuality after the gun goes and to make a snap informed tactical decision when something that was not predicted occurs.