Speaking as someone who becomes ill for a prolonged, random period almost once every month, definitely plan ahead. Check in with your officer(s) ahead of time to figure out or have a concept of what their goals should be and write it out. Planning a couple weeks ahead would be beneficial for a commander if they were to suddenly become ill once a Flight starts coming around. From there on, it should be smooth sailing despite sickness and health.
Think up of many possible solutions for how to improve certain skills. Everyone learns differently, so it would be good to have a list of experience (what elements helped you to improve in that skill) and what you think would be good solutions for areas of improvement. If they worked for you, it will likely work for others too! ;)
Get to know your officer(s)! Help them to open up since you might not know if they're shy and not likely to communicate internal conflicts related to the Flight. Talk things out with them if needed, and encourage them to communicate whenever they are in need of something. Don't be dismissive about how an officer is feeling. Instead, help to guide and support them.
Remember to put your health and well-being into consideration! If you think you can no longer run or continue a Flight due to IRL considerations/commitments, let your officers and colleagues/local SCP Wiki staffers know. Don't push yourself unless you know for sure what you're doing. Love and take care of yourself above all else! <3
Log your commandership work so that you'll have references for future Flights. It will get annoying to have to remember and type the same things over and over again. Logging your work would save you time in the future, mmhm!
Model off of your favorite mentor(s). It's like that with teachers IRL, and those are usually the best teachers. If you've been a part of a Flight as an officer before, you have a major advantage. Use it! Pass on the knowledge and tradition! DO IT AS IF YOU HONOR, which you do, YOUR OWN MENTOR(S)!!!!
Most important of all… have fun! Flights should be a learning experience for every participant, so try not to stress out over making mistakes. That's how we learn. And of course, don't be afraid to ask questions as a mentor. There's always something new to learn and improve on. Be accepting of knowledge and experience, and you'll do great things!
Just gonna sneak this last one in… know when to put your foot down. If an officer isn't listening and exhibiting unacceptable behavior even after being asked to stop, they're not worth your precious time. It would be difficult to help someone if they're not willing to help themselves to your service. If you ever come across anyone like this, let staff know immediately. And be sure to send the bad officer a "You're fired!" PM! :D
