Good on ya!
I'm not going to talk about how to run a minstrel. LOTRO says it's medium difficulty, and I suppose that's true. It is a pretty powerful class, Theabromine is currently level 41 and I can fight some that are around +4 levels to me, including elites. And my armor definitely needs upgrading!
But I'm not going to talk about that. I'm going to talk about music.
First off, all of the advice that I'm going to give is strictly on a YMMV basis: your mileage may vary. Other people may disagree and say I'm totally wrong. That's fine. This is stuff that's worked for me, it's things that I've experienced. In many cases, I've done things the hard way, and I've learned by doing it that way. And I'm OK with that.
So it's worth what you're paying for it.
Let's talk about leveling, this applies for both your main minstrel and any additional band members. The goal here is to play music. I'm not going to talk about converting MIDIs, that can get VERY involved, I'm taking about actually leveling your minstrel. The best way to do that is through farming.
That's right, farming. Tilling the soil. And the best way to do that is with money. If you don't have a higher level character with money, or a friend willing to give you 3 or 4 gold pieces, then you're going to have to adventure a bit until you've earned some coin or gotten lucky with Hobbit birthday presents. Personally, I'm fond of the hothouse outside Thorin's Gate for leveling my minstrels, but farm wherever you like, they're all good.
Keep in mind that if you're running a free to play (F2P) account instead of VIP, you're normally capped at 2 gold. If you've got someone else sending you gold or materials in lieu, you may run in to situations where you've got more in reserve than you can work with, and you'll have to logout that character and come back in to have access to those additional funds.
Now, your main musician is a minstrel-class, are they not? Every class in LOTRO can play instruments, but there are limitations. I have a defender in my band, she mainly plays theorbo, but she plays quite a variety and I've trained her to play pibgorn. You'll have a much easier time making sweet, sweet music if your musician is a minstrel, as are most of the members of your band. I won't name names, but there's a band that I know that's composed of mostly hunters, and the leader occasionally gripes, asking what they were thinking, making them hunters.
Having said that, there is an advantage having a high(ish)-level hunter in your band: transportation! You get your band together, and your hunter can instantly pop everyone over to Michel Delving or back to Bree. That could be very handy! And again, if the hunter is high enough level, they can play a lot of instruments.
Now, I believe Captains can also port groups to distant places, but I haven't been running my captain enough recently or to a high enough level to know. Hunters are very easy to run, so I personally would go with them.
When aiming to run a large band, you want to train them up to a minimum level of 15, 20, or 25. These are skill levels that let you play the most instruments. 20 and 25 are required for minstrel-class to play pibgorn. Only minstrels can play the level 25 pib, I'm not certain yet if there's any difference in sound quality between the two.
In conclusion, while any class can play music, minstrel-class is best. Farmers skill up the fastest. Aim for level 20 or 25 for NPC on F2P accounts.
And play, Play, PLAY! I play mostly on Crickhollow, it's a very friendly server for both new players and musicians. We have a weekly Friday night gathering outside The Pony in Bree, and you can find people most evenings at South Gate jamming. We form up a loose circle and alternate play going clockwise.