I thought I'd share what I do with a brand new airgun before shooting it. The first thing I usually do is give it a good visual inspection to make sure there's no exterior defects/damage of any kind. Once that's done, I check the stock screws to make sure they're snug. Then I get it ready for a barrel cleaning. Cleaning the barrel of a new gun BEFORE shooting it has been something I have always done with my powder burners, and I feel it should be no different with an airgun. On break-barrels I cock them and leave them open during the process (a few minutes).

I then take my weedeater line (pictured below), which has one flattened end and one sharp end. A whole coil of this stuff is a couple bucks. I'll heat one end with a lighter until it's soft, then press it against a hard cold surface (like a table). It dries very quickly. I'll then poke a patch through the sharp end, pull it against the flattened end, soak it with some goo gone, and pull it through the barrel once (from the breech out the bore). It helps to put a rag below the breech to catch some of the excess goo gone. I'll let that sit for a few minutes, then start pulling dry patches through one by one. Some barrels aren't that dirty and some come out with all kinds of crud, especially on the first run. I use .22 sized patches - they work good for both .177 or .22 rifles. On .22 barrels I'll double up on patches.

Once they start coming out pretty clean, I'll load a round and fire the rifle. I'll fire another 5-10 rounds to clear out any excess oils from the chamber, then start sighting her in. That's it folks!

I got into the habit of using JB paste on my last couple new guns before i fire them. Just like you said, the barrels are terribly dirty from the manufacturer, plus the rifling is often a bit rough. I guess that stuff from jb has a tiny bit of abrasive it it and it kind of wears in a barrel before you take the first shot. It improved the accuracy of my existing rws 350 so i started using it on my new aquisitions right off the bat. All are accurate so i can at least say it doesn't hurt anything. It DOES seem to leave a bore shinier than just cleaning alone and i guess that any rough spots felt while running the polishing swab up and down disappear within 5 or 6 passes. Then you clean it well and go shoot some bullseyes. NOTE: some bores may be made of materials not suited to an abrasive type cleaner so i'd check that out beforehand...

I like to go through my trigger group as well before shooting, adding spacers to tighten up slack and filing rough spots somehow makes a gun more "yours". The molylike lube i use is some 1970's era military stuff but i covet the bottle as its the clingiest, slickest crap ive ever come across.

On my cheap ole B-31, i went ahead and sanded the stock down and refinished it and reblued(sorta) the gun before shooting it much, if at all. Polished the barrel and tightened all up like jon said. Got the scope mounted , then started shooting. Truely the gun seems much more your own creation when you've taken the time to preform pm and mods before ever shooting the thing. Its like you've built it...J