Just shove it down the drain, bulbous end first, as far as you can. If there is a can type trap between you and the clog, forget the snake. It'll just coil up in the trap like a cobra in a basket and go no further. Assuming all is well down the line, the debris will just happily flow on down to your local waste treatment plant to be processed into fertilizer. You might remember we called this meeting to discuss why your drain cleaner doesn't work for you.
Chances are, the clog is past the trap.
Keep in mind, if the drain is completely clogged, water will not pass. That means often there is a pipe full of water between you and that clog. Even if the drain cleaner is heavy enough to fall through the water, when the drain clogging debris is past the trap, most of the cleaner will stay in the trap and any that doesn't will be too diluted to work. So, if you expect the chemical drain cleaner to get you flowing again, unless the problem is in the trap, you will be disappointed. Always read and follow the label directions.