Most miners will need to use their metals to level up their other professions, however now would be the time to focus on selling; level later when the metal prices have normalised. Your first priority should be to level your skill, and frankly the easiest way to do this is to head back to Outland. The nodes in Northrend are harder to find (especially if you can't fly yet), over farmed and you're likely to get ninja'd too. I've managed to get my skill up to around 425 in Outland with relative ease. The zone's hardly have anyone in them except Death Knights (who can't fly) so you can fly around and you'll find an abundant supply of nodes. Fel Iron & Adamantite will give you some skill ups, but Rich Adamantite and Khorium will get you well into 420 skill. If you don't want to do this, it's still worth making a detour to Shattrath if you're heading off to your normal capital; The Barrier Hills. This small hub just on top of Aldor Rise is every miners secret farming spot. It usually spawns 2 or 3 nodes of Adamantite, Rich Adamantite and even Khorium. These days there is almost always a few nodes there because no one is using Shattrath. A very easy way to get cheap skill points before heading off to Stormwind or Orgrimmar. If you have the bank space, I'd save the Outland metals for a few months because they are worthless now, but are likely to shoot back up in price (just check the price of Iron, Mithril or Thorium). It's so easy to level in Northrend that you're likely to end up in zones where the nodes are too high for you to mine, this can help you stay ahead of the curve and not waste nodes.
This should put you in a fairly comfortable position to get your skill to 450. Most of the new metals are selling for crazy prices at the moment. If you want to make some real money, getting to 450 is vital because you can begin to smelt Titan Steel, which is going for 500g per bar on my realm, and this is the cheapest price. You can only smelt one every 20 hours, so supply is low and demand is high because they are required for all the best recipes in Wrath. Even if you don't have the materials to smelt a bar, advertise in Trade Channel to do it for other people. A huge number of people are after them and you can make some serious money off tips (make sure you agree a price before smelting). The good thing is the price of these bars is likely to remain fairly high because you need 12 of them to make the new Engineering Motorbike, not to mention countless other high level recipes. I would definitely recommend getting to around skill 420 in Outland, and then hopefully you can hit the rest of the points quickly in Northrend. If you have not maxed the skill by level 77, the first thing you do with your flying mount is to finish off leveling mining. Every 20 hours is money lost!