Welcome to the touring world.

My tips:

Just get out and tour. In my opinion folks tend to make a way bigger deal over getting started than really makes sense, especially if you have some camping experience.

Nothing wrong with some shakedown cruises, and if they are what you want there is nothing wrong with continuing to do only short tours, but... It is also quite possible to do a more ambitious tour as a first tour especially if you are a fairly experienced camper. We did the full Trans America as our first tour and met quite a few others doing likewise. In general they all seemed to be doing fine.

Keep your gear weight down but do not get too into the gear hype that is so often rampant here. This goes for the bike as well as the camping gear. If you want to get real nice stuff that's fine, but it isn't necessary for success.

If you want to spend more on some items I'd suggest that they be the camping gear where that will save you weight by spending more (tent, sleeping bag, and sleeping pad come to mind). That said you can get by fine with inexpensive items, we did on the TA, but I have since upgraded items where there was a substantial weight savings for doing so.

What I personally would recommend avoiding like the plague are things that are both more expensive and heavier. Surly Nice Racks, and Arkel panniers come to mind as examples of that.

There is always a lot of talk about stealth camping here and on other forums. If that appeals to you that's great, but don't get the idea that it is the only way to go or even the only inexpensive way to go. I have found that it is easy enough to find cheap or free places to stay with no stealth required. I will stealth camp in the rare situation that I need to but I'd rather camp for free in plain sight. Where there are hiker biker sites or other reasonably priced camp sites I use them, the rest of the time I camp in town parks, someone's lawn, or a church yard (the latter two only with permission).