Hi Scott,
apologies for the delay in jumping in, as a Dublin native perhaps I can help . . .
As Simon says, there really are no does and donts, just have a good time.
First off, your most critical task will be to get accomodation sorted in the Isle of Man asap, as that will be in considerable demand. Bear in mind that while it is probably ideal to be based around Douglas, there are other locations such as Ramsey or Peel that may be just as attractive. Accomodation in Dublin is plentiful, but can be expensive. You also want to choose your location carefully, from the point of view of safety and accessibility. If you want to run a few suggestions by me in messenger, feel free to do so, I'll give you the best feedback that I can. While I have spent most of the last 21 years in France, I was based in Dublin during the Covid years, so I do have a good bit of recent knowledge of the city.
If you have not already booked your travel between Dublin and the Isle, it may be a good time to decide whether you want to fly or take the ferry. The flight is about 25 minute duration and is quite literally over before you know it. The ferry on the other hand is more like 3 hrs duration, but that will be where you will make your first new motorcycling friends. (At the bar of course). The ferry approaches the Island via it's south coast which is always a a lovely experience.
You might want to consider which means of transport gets you there early in the day, and leaves late in the afternoon to maximise your time there.
More than likely the visa you will use to enter the Republic of Ireland will suffice but check beforehand. The situation not totally straightforward
e.g. The Republic of Ireland is in the EU but is not part of the Schengen zone.
The UK is not in the EU and was never part of the Schengen zone
The Isle of Man is not in the EU and is not part of the UK.
The UK, Republic of Ireland and the Isle of Man are all part of the Common Travel Area so that may be your key unless you already hold RoI or UK passports. You should find guidance at
https://www.gov.im/categories/travel-traffic-and-motoring/immigration/visit/Bring plenty of motorcycle themed gear, even to include HD or Indian

Be ready for rain, but you could get lucky, it will all be part of the experience. You can also get 3 seasons in one day. I remember helping my brother prepare his Yamaha TZ for the lightweight, and while it was bright sunshine on Glencrutchery Road, the mountain ascent/descent had rain and the summit was shrouded by fog. So be prepared for all eventualities.
I am sure you will have a great time there, and feel free to use me as a resource at least for the RoI aspects.
Kev