Tools, Sharpening and Power Machinery - Self-drilling screws

Trying to drive say a #8 self-drilling screw into a steel post approx. 3/32 or 1/8 thick. Not having success. What tools do I need? Any special techniques?

Crazy

There are self drill screws made to drill into the material you are working with.
I suspect you are using ones that are made for light sheet metal.
Sheet metal self drills have a thread that looks like a standard sheet metal screw with a drill bit end.
Screws for the material you are working with have the drill bit end, but have a finer thread, a lot like a machine screw. They also are a bit heavier than a sheet metal screw and usually come in a hex head.

Gosh, thanks for info on proper screws. Would a hex-head screw work better than a philips head? Am using a 14.4V cordless drill. I have seen advertised gadgets that seem to keep screw from wobbling. Would that be of help?

Hex head screws are more solid in the bit. A magnetic tiped bit is available that keeps the screw from falling out.
In Canada the Robertson or square recess fasteners are most common and don't tend to wobble.
A poor fitting screwdriver bit or pushing too hard on the drill will cause it to wobble.
A trick that could work if the material is too thick for the screw is to predrill the hole just slightly smaller that the screw.
It may go in easier, but it won't have the holding power it should.

Also with self drilling screws sometimes drilling slower actually drills better. The screw kind of digs in better. Good luck