Smack it harder, after you've isolated the pack (one end) and make sure it's not going to move on you (cup your hand)... Use your 'pimp' smack...
Of course, if you also make a starter, then it won't matter if you popped the packet or not. The packet, for me, is just to prove that the yeast is still viable IF I've had it in the fridge for a while. I usually pull it from the fridge an hour or two before I make my starter. Let it warm up, smack the biotch, let her swell up and then pitch into the flask on the stir plate. 24 hours later, it's ready to rock and roll in the brew wort. :rockin:
Making/using starters is very simple/easy. IMO, there's really no valid reason for not using one. You'll get much shorter lag phase times when using a starter. Even shorter when you also use pure O2 to oxygenate the wort before pitching the yeast (the brew, not the starter). With a stir plate, you can make much smaller starters.
For your own education, use
Mr. Malty to show what size starter you should be making. Try the different methods with the liquid yeast (simple starter through stir plate)... For the exact same OG and batch size, there's a huge difference in starter size from one to the other (simple to stir plate). For example, a batch I have coming up, with an OG of 1.068 (6 gallons into primary) would need a 4.6L simple starter, but only a 1.72L starter on my stir plate... That saves a good amount of DME (helps the stir plate to pay for itself pretty fast)...
Any batch with an OG of over ~1.030 (for 5 gallon batch sizes) WILL benefit from using a starter. Since most of us know what we're brewing at least a week (or a few days) before that day, there really is no excuse for not making a starter. You can also make a stir plate for pretty cheap money (if you want). Or just buy one, with a range of prices/options being available.