I'm back again! Rejoice! Hope you had a happy eastern. Although it's not really over yet...
To warm myself up I'll just make a little post about some things to think about when leveling a rogue/cat. Rogue is in fact the only class I haven't played to 80 yet, but I have started one and I am thinking about deleting my old bank alt one and start one fresh on my main server. I have to give them a proper chance!
While playing my lowbie rogue I noticed some things that are valuable to think about while questing.
First of all, unless your best friend happens to be a rogue, or you already have one yourself - max your lock picking. It always annoys me when rogues don't do this. There is really no reason not to. It takes way less time than most other professions (although it's not really a profession, I know). Glyph it with Glyph of Pick Lock (which reduces cast time from 5 seconds to instant, a must have!) and create a macro which uses Pick Pocket before using Cheap Shot on a mob (which you get at level 26). These two combined will not only make skilling lock picking very easy, you'll be plenty rewarded since lock boxes often contain good stuff. Potions and poisons for example, and even the occasional green (and even blues!.. even epics!). So seriously... get lock picking.
EDIT: Here is the macro I use btw. I am sure it can be done in a way more neat and cool way, but this works.
#showtooltip Cheap Shot
/cast Pick Pocket
/cast Cheap Shot
So that's the first tip, my second one will be one that might sound obvious. Keep a good eye on your skills. Which skill has the highest dpe (damage per energy) will vary greatly from one level to the other. At one level you might need two combo points for an eviscerate to be worth more dpe than a simple sinister strike, the next you might need three, depending also on your talents. The same goes for all finishing moves, so keep track on it, if you're interested in maximizing your efficiency (and you are of course!).
Keeping track on your skills to always use the most efficient one is of course something everyone should do, no matter if they use mana, rage or energy. But because of the nature of how energy works - you only have one set amount to use at every given moment - this is particularly important to maximize rogue/cat efficiency. A warrior could get 100 rage the next second, a caster could use a pot or just go all out and drink after the fight, this isn't really an option for an energy user (although there are energy pots to use of course). You've got your 100 energy (unless you talent for more) and you have to use them the best you can, the amount you can use at any given moment is very predefined. The same goes with DK runes for example. That means using 20 energy on a less good skill is more wasteful than using 100 mana on a less good skill. There is still more mana to take from (unless of course you're close to oom in which case this might be important as well).
Thinking about "small" things like this is what make the big numbers ;)