I'm not an expert on this particular model, but I do know it's a special version of the New Model Vaquero. It should be fine with any of your factory "standard" .45 Colt ammo, or any of the somewhat less powerful "cowboy" loads.
Do not use any of the high power, high pressure loads sometimes labeled as "Ruger only" or "Ruger or Thompson-Center Contender only." These are supposedly safe in the Ruger Blackhawk, which has a larger, heavier frame and thicker cylinder than the New Vaquero. Or in the old-model, original Vaquero, which had a Blackhawk frame. But the New Vaquero is built on a frame the size of a Colt Peacemaker's, lighter and more trim than the Blackhawk's.
(Personally, I never liked those high-powered .45 loads. The .45 Colt is a mean, MEAN old thumper in its own right, and I always felt that if you wanted a .44 Magnum there was nothing wrong with getting one of those in the first place. But a lot of people disagree with me, and that's fine. No hard feelings.)
In my .45s I've used the green-box Remington standard loadings without any trouble.
For you, to see how the thing works, might I suggest you try some of the commercial cowboy loads first? I had good luck with the Winchesters and with Magtech, whoever they are.
The cowboy loads are lower powered for less recoil, although in my opinion they're still nothing to be sneezed at in the power department. The big thing is that they are usually less expensive, and they're enough to show you how the weapon is working for you. The first thing you want to know is whether the revolver works properly and about where the bullets are hitting on the target, and the cowboy loads are fine for that. They'll also give you a supply of fired brass that is as good as any, in the event you want to start handloading. I definitely recommend that for the .45 Colt. It's fun, doesn't cost that much to get into, and it will save you quite a bit of money in the long run, unless you don't shoot that much.
Since the Vaqueros have fixed sights you want to get your experimentation with ammunition done early. Someone can step in and correct me here, but if I remember how it goes, all else being equal at 25 yards or so (the usual "formal" target range) a heavier, somewhat slower bullet will hit the target higher than a smaller, faster one. You might want to choose which loading based on which hits closer to the target for you. The other option is to file the sights to bring yourself onto target. Obviously this is something you only want to do after you've decided what loading you're going to use for the rest of your life.
There are all sorts of articles out there telling how to do this.
Have fun! 'Cause if you aren't having fun, you're not doing it right.
