Using a guide can sometimes increase the gaming experience. I've used one several times before Cataclysm because the guide would pick up all or most of the quests in the zone and do them in the most efficient sequence, meaning I didn't have to run around everywhere just to run back around everywhere for a follow-up quest. Cataclysm did a lot to make the lower level zones linear, but sometimes you just want to make sure you didn't miss any quests.
Unfortunately, the guide I'd recommend has not been fully updated to Cataclysm yet, so I'll link to the main page and you can choose what you want. There's even an addon for those guides in case you don't have a second monitor, or just don't want to Alt-Tab every time. -link-
When looking up leveling guides, be aware of some things:
1. Never, ever pay money for a leveling guide. It's a waste of money, especially since most of those guides are just blatant copy-pastes from another, usually free, guide.
2. Never, ever pay money for a leveling add-on (or any add-on). Not only is it silly to pay for an add-on, but it's also not allowed by Blizzard. Add-on developers can request donations, but they can't limit their add-ons to payers - it has to be free for all.
3. Be careful when googling "leveling guide" as a lot of those sites are malware infested cesspools created for the sole purpose of luring in newbies so that they can get various malware onto their computers. If you suspect you've visited such a site, run your anti-malware programs.
And always use common sense when browsing the internet and downloading stuff. If you get a bad vibe from the site, close it. Don't ever type in your password or account information on a website that isn't Blizzard's official website. You don't need to log in anywhere to download an add-on. Never click links you don't know the destination of and never let a website run a program you're not familiar with.