Since Cataclysm has been out for a while and that most people probably don’t do Lich King raids any longer (except for past achievements), there is a basic issue of gearing up a new toon after finishing Northrend. I found that for my first toon or two, it was difficult for the first few quests without having reasonable gear. My toons had ilvl 178 or below gear from Northrend, I had under 20k health and my damage sucked. As a result, I came very close to death easily in the first half until I managed via questing and the occasional green drop to overcome these obstacles.
That said, my first two 85s were a paladin tank and blood death knight. So in those cases, I had better survivability compared to my other toons. But with my feral (cat) druid for instance, she survived at the skin of her teeth. Afterwards, I decided to evaluate my situation a little more, especially as I worked on my shaman and warlock (I imported my hunter from a different server, but he had quite a bit of 264 gear). Eventually, I figured a few ways one could deal with this situation.
First, check your auction house. There’s some decent gear for levels 78-80. If you don’t have an 85 and find yourself struggling a bit, that might be your best bet. Second, see if someone can help craft some gear. For my warlock, shaman and warrior, I put quite a bit of effort into taking a ton of mats and making a few pieces of gear for them. Recently, my warrior hit level 80 and I had managed to save up quite a few pieces of gear and did some crafting via my paladin to make things like shields and a near complete hardened plate set, which is usable by an 80.
If you don’t have professions and lack gold (or don’t want to spend anything) but have an 85 hanging around, one suggestion is to farm 78-80 gear. In Mount Hyjal, there’s a small zone near the Firelands raid where a particular mob called the Twilight Subjugator resides. This mob occasionally drops gold and greens, making it a reasonable farming spot with a decent respawn rate. Heck, even before leaving Northrend, you can use this spot (or other gear you may encounter as you quests in the Cataclysm 80-82 leveling zones) to give your new toon a slight edge.
Similarly, other people will be wanting the same thing. So if you find gear that’s not relevant to the toon you want to twink out, you can probably sell it for a decent price on the auction house yourself.