Although doing smoking tricks is by no means the healthiest party stunt you can pull, there's no denying that it's impressive. There's something very aesthetically pleasing about the way smoke moves, and being able to manipulate it with your mouth is a skill to master. Here's how.
Blow O's or smoke rings. To do this (and most smoking tricks) you should not take the smoke into your lungs but into your mouth instead. The reason for this is because you will need to retain the smoke much longer than if you were simply inhaling. Holding smoke in your lungs for these tricks will make you cough, and that doesn't look very cool. Use the muscles in your cheeks to suck in a full mouth of smoke, then form a tight "O" shape with your lips, making sure that your cheeks are stretched taut. Make quick, precise movements with your mouth to contract it slightly, and do this several time in succession. A stream of smoke rings should follow one after another.
Create another trick--blowing one smoke ring through another. Contract your mouth muscles to push rings out until you figure out how to make some O's large, some small, some fast and some slow. This will probably take a good deal of experimentation before you get it down. Position your head so that you're aiming at a downward angle. Blow a medium-sized, slower moving "O." It will drift upward and expand slightly as it floats up. Right before it reaches about the same level as your mouth, blow a smaller, faster moving "O." Keep practicing with the size and speed of your O's until it looks right.
Learn the French inhale, arguably the sexiest smoking trick. This is when you take smoke into your mouth, allow it to drift out of your mouth while simultaneously inhaling it through your nose and then exhale through the mouth. To begin, exhale completely so that there is as little air in your lungs as possible, then fill your mouth with as much smoke as you can. Do not blow the smoke out, instead simply open your mouth and allow it to drift out and upward. It may help to jut your lower jaw and bottom lip forward slightly. Once the smoke is drifting upward, inhale long and hard through your nostrils. This will draw the stream of smoke through your nose, into your lungs and back into your mouth. Finally, exhale through your mouth.
To make the French inhale even more impressive, blow one large "O" out of your mouth instead of just exhaling. The reason that it's wiser to stick to one big smoke ring rather than several smaller ones is because the tendency is to lose a lot of the original smoke during the process of the French inhale. This will leave you with significantly less smoke to work with, as well as less lung power.
Inhale a drag, allowing a wisp of smoke to escape your lips and then suck it quickly back into your mouth. This trick isn't as easy as one might think. Fill your mouth with a little less smoke than you used for the last tricks, then form a small opening with your lips for the smoke to drift out of. Once you are able to see a small but thick wisp float in front of you, use the same opening of your lips to gently suck it back in. Do not inhale sharply, as this is likely to make you choke on your mouthful of smoke (it enters your lungs much more quickly this way than if you're slowly dragging on a cigarette). It might help to lean forward or follow the wisp slightly with your head as you suck it back in.
Don't buy a whole pack of cigarettes to practice these tricks. You could ruin your throat and make yourself horribly sick to your stomach. This isn't something that most people can typically pick up overnight, so have patience and take your time mastering these skills.