Following the standard lock advice makes sense: Spend money on a good, secure lock; feed the lock through the wheels; et cetera. You'll want to follow much the same advice in these questions:
...with the additional wrinkle that you get to control the environment where you're locking up, essentially that you can decide what you lock the bike to, as opposed to when you lock up in a public area and have to find a good lockup location.
If you live in a very safe neighborhood, you'll want to scale back some of this appropriately.
Bike Parking Racks
This is probably the most secure option. Get yourself a small, sturdy rack and attach it to the floor by drilling pilot holes in the (assumedly) concrete floor and bolting the rack there. There are several varieties, including metal racks (your best bet) and small bollard-type racks. (That last is the sort you see on sidewalks, essentially a post with loops in it to feed the locks through.)
You can also make your own rack, either by building an entire rack (practical if you have several bikes) or simply screwing heavy-duty eyelets into the floor and running a cable lock through it. (Not as convenient, but certainly a cheap, reasonably secure option. As others have indicated here, there are products available to install the latter.)
Locking to Existing Stuff
Not necessarily a promising option in this case, but perhaps there are a few things that have been overlooked here:
If a bike rack isn't in the cards (as above), people often can also lock to garage shelving or other permenantly mounted stuff. This is less convenient and messier than a rack, but this can work. One has to make sure that whatever they lock to is securely attached to the garage, or, at the least, extremely heavy and clumsy to move.
In this case, there's nothing to lock to... I assume that means this means there's certainly nothing obvious, like shelving or furniture. Have you taken a look for unused pipes or sturdy shelf bracket? Are there any fittings on the walls that could be used for this?
Do you have anything you store in the garage that's very large and heavy, like a dresser or a headboardor a tool bench? I've seen people lock bikes to cinder blocks... and nothing else; you want something that would be prohibitively difficult to move.
Ask yourself what else you store in the garage. Unused boiler? A potbellied stove you haven't gotten around to installing? A broken car? All of these space-wasters are hard to walk away with, and can make for great impromptu bike anchors.
Overall, I think the eyelet installed in the floor (or wall) is the best solution here.
It's worth mentioning some general advice here: I've seen bikes locked to other bikes and nothing else. I've even seen bikes locked so that the wheels can't turn, but one could pick up the bike and carry it away. A determined bike thief can even pick up a bunch of bikes locked to each other and toss them all in a van.
Also, additional security can be had by simply hiding the bike so it's not as visible, perhaps behind a bench or a car or a shelf. Keep that in mind when you pick a lockup location in the garage.