Before installing your freeze...
Before installing your freeze plugs, take a moment to make sure the holes in the block don't have any dirt or crud that will keep the plug from making a good seal. If there is any, you can usually get it out with lacquer thinner, a Scotchbrite pad, and a little effort.
For racing, you don't want...
For racing, you don't want to take any chances with a coolant leak. You can use Loctite (either red or green) to help cement the plug into place. The Loctite not only helps keep the freeze plug from working loose, it also expands to seal any scratches or gouges in the block's freeze plug bore.
There are specific ways to...
There are specific ways to install freeze plugs without warping or otherwise distorting them so that they won't leak. This is especially critical with softer brass plugs. Never hit the plugs directly with a hammer. Many professional engine builders will have punches sized specifically for the plugs, but you can do the same thing with a large socket. For Chevys a 11/8 socket is just about right. Try to drive the plug in square with the bore and just until the lip of the cup is flush with the block.
The problem with using a socket...
The problem with using a socket is it can be difficult to get a grip on it and drive the plug in nice and even. If you have a seal driver set, it makes driving freeze plugs a lot easier.
The handle on the seal driver...
The handle on the seal driver gives you better control. Use a size that completely covers the plug. Then drive the plug into the bore until the seal driver contacts the side of the bore all the way around. This ensures that the plug is the correct depth and square to the bore.
Don't forget the rear cam...
Don't forget the rear cam cover in the back of the block. This should be done before the block is on the engine stand because you won't be able to reach it once the block is bolted up. Again, use Loctite and drive the cover until it is flush with the block.
In high-performance applications where a failure can be worth big money, engine builders will often "pin" the freeze plugs to further ensure they won't come out. The process is fairly simple and you can do it yourself. Drill three holes just above the lip of each plug (on the chamfer of the plug bore in the block). Use a No. 38 bit and drill the holes on a 45-degree angle until they are approximately 0.300-inch deep. Now you can tap the holes and use button-head screws or use freeze-plug pins made specifically for this task. These pins save you the effort of having to tap each hole. Just use Loctite on the pins just like you do the plug itself.