I know it's not quite appropriate since summer is ending, but better late than never: I've had the honor of working with make up artists who are well known in the industry and a trick that a lot of them use is applying Dr. Lipp as a highlighter instead of the normal stuff. It gives you a far more glossy appearance and is great for beach-inspired looks. Apparently it was even used liberally on Jlo in her Into You video beach scenes. Pretty much all the make up artists and other models I know carry a tube of this stuff everywhere since it's so versatile - it can be used for cracked cuticles, lips, dry skin and (what most people are unaware of) used to add a nice shine to wherever you dab it on. I'm not sure if you can use vaseline as a cheaper alternative, but I'd imagine that in a pinch, it'd do as well.
Other things I've picked up over the years: when applying red lipstick, I now lightly apply foundation on my lips first, apply the lipstick, blot off then reapply. The foundation gives you a stronger, 'truer' color that looks more like the lipstick in the tube and the blotting off and reapplying makes it last longer. Also, using a toothbrush and lightly brushing them before helps flake off dry skin when they're chapped. Lush sell some really nice flavored lip sugars that do the same job and taste great as well. Either way, you achieve smooth lips and your lipstick will glide wonderfully over them.
There's others I'm sure I know but I'm heading out and they aren't really coming to mind, so that'll have to do for now.