I had the same question a while ago. Easiest route for me was a combination of the following:
1. Get the power/toughness/vitality Soldier sets from the Orr karma vendors in the cathedrals, when unlocked. They’re roughly 40k karma each and while you may not have much karma stored up if you’ve just dinged 80, it goes quickly. Each flask from the daily achievement is 4,500 karma, you get 10 for the monthly, and in between karma from events and WvW. Save up all the flasks and pop them when you have a Karma booster and guild bonuses. Pick selectively which bits of gear you need from which cathedral (Dulfy.net got a good list), most pieces come from Cathedral of Verdance. Start with chestpiece and then legs, these give most stat bonuses. Less and less people still do the cathedral unlock events so keep an eye out when they are clear (no crossed swords on them on the map).
2. Get Draconic crafted gear from the AH or make it yourself with armorsmithing. This gives you any stat bonus you want, I’d suggest you pick up pieces of Knights, which is an allround good set and hard to get from dungeons. Armored scales are around 6s, orichalcum and gossamer around 2s, so only the ectoplasm is actually expensive. IF you salvage all your rares and merge your greens into rares at the mystic forge you should get enough ectos in a few days.
3. Start running explorable modes of dungeons. One run is roughly 66-69 tokens; you can get some pieces for 180 tokens (gloves, boots, etc) and some others for up to 300 (legs, breastplate). As with the karma vendors, plan in advance which ones you want. I wanted some Berserker pieces to increase my crit damage; those come from CoF which is amongst the easiest of the dungeons (especially path 2). Soldiers come from HotW and a few other places. Knights pieces are hard to get from dungeons, only from SE or Arah.
4. Weapons: this should probably be your first upgrade since you REALLY notice the difference between a rare and an exotic. Again get them from dungeons, or crafted, or from the mystic forge. I started out with a Mystic Claymore: 30 mystic coins, 50 skillpoints, and some orichalcum crafted pieces. Not that expensive and an enormous upgrade. It’s got berserker stats which was just fine for me. Skin is a bit futuristic/asura style but you can transmute it if you don’t like it.
5. Jewelry: mostly crafted. You can get some with tokens nowadays, but the exact stat combination you want may not be on them. Those five pieces you may simply have to buy from TP or craft if you’re a jeweler. Don’t forget that you can have, say, an emerald (=knights) necklace but with ruby (=berserker) gems in it, that gives you more customization options. I found the intricate ruby gem a good way to rack up more precision and +crit damage quickly without compromising too much on other stats.
I’ve just finished gathering two sets: one Soldiers for WvW (From karma) and one Knights for PvE (crafted). Now I need to start getting some more interesting skins, especially the karma pieces look very spikey so you may get bored with it quickly.