Everyone's tips will be very different, especially when it comes to whether supplements are needed or not. You could end up spending as much on protein powders/collagen and vitamins as you do the Mounjaro itself. So think about your own particular needs and not just what everyone else takes.
If you eat enough protein you don't need to supplement, if you are younger collagen might do nothing for you as you have enough of your own, if you don't suffer from constipation you won't need anything for it, probiotics are not necessary unless you have symptoms of an imbalance in your gut health etc.
Some (there are lots more!) to research and look into -
You don't need to increase you dose every pen, even if you have one of those providers that imply you do. Many users have stayed on lower doses and had significant losses.
If you are unlucky and someone who gets significant unpleasant side effects speak to your provider or local pharmacy for help - they can prescribe anti-sickness etc tablets.
There is extra liquid in each pen where you can unofficially take a fifth dose if you can access it. The hard twist method appears to no longer be working for newer pens so you will need a syringe (don't buy from amazon).
Always prime to check the needle is working before injecting. If prime or injection doesn't work try changing the pen needle. If your provider doesn't send a couple of spare pen needles with each order it is worth asking them to and/or buying a box.
Look at other threads about click counting once you are more confident with the medication and know how your body is responding. For your first pen stick with the standard 2.5mg for 4-5 doses.
Personally I think the suppression effect is 50% medication and 50% willpower/habit. Don't expect the pen to do it all for you.
Calorie count/food track using an app at least in the beginning - weigh and track everything including oils and spreads - MFP (free) or Nutracheck seem to be the most popular. Both track weight and calories/nutrients (such as protein) over the day/week. If you don't know your cutting calories you should be aiming for using the TDEE calculator.