tl;dr: Besides practice, there's nothing else that will help your presentation more than a rock-solid, handy, simple remote. And this one shoots out LASER BEAMS!
I've been giving presentations here and there for the past few years, and in the past, I've been tethered to my computer as I've needed to present slides, play videos in slideshows, and generally control things.
(Embellished with my little 'property of' sticker.)
I started using the Apple Wireless Remote for some presentations, but it required line-of-sight to the IR port on my old MacBooks, which was bad for two reasons: first, I still had to be behind my computer when I wanted to change slides, and second, newer Macs (like my MacBook Air) no longer come with IR ports.
A friend lent me his Kensington Wireless Presenter remote once, and I was hooked. The remote is solid, works from at least 50' away (that's the farthest I've ever ventured from my computer during a presentation), and lasts pretty much forever. Right after that first presentation using the Kensington Wireless Presenter, I bought one on amazon.
The remote is very well-built. It conforms to my hands perfectly, and is slightly rubberized to prevent it from slipping out of your hand. The rubberized buttons are easy to press, and click very resoundingly when depressed. I rarely use any button besides 'forward,' but all four work the same and are easy to reach without looking.
The USB dongle that plugs into your computer clicks into the remote itself, so it's hard to lose, and it's small enough that I can still plug it into the side of my MacBook Air with no problem on any podium.
The laser pointer is very bright, and the laser point of light can be seen clearly across a wide room. You can even light up Sprite water bottles if you want, to give people a little surprise, but keep the laser away from people's heads, please!
I've used my remote for over 10 presentations now, with not one missed click, and have not replaced the batteries yet. I have no doubts about this remote, and will probably just change the batteries once a year to be sure they never go bad.
The only improvement I would make is the addition of a low battery indicator, just to provide a little more peace of mind for those times when I don't know how long it's been since the last time I used the remote.
If you give many presentations (or just a few), having this little remote is a very good idea. The laser pointer lets you highlight important parts of a slide or diagram, the buttons click very solidly (so you know when you hit 'next' or 'previous' and don't get stuck trying to get to a certain slide!), and the battery lasts forever.
You can buy the Kensington Wireless Presenter with Laser Pointer (product #33374) from Amazon for about $35.