Here is a good guide, best to read first.
I''ve just been levelling from 11-21 and here's what I found. Perhaps others could contribute their ideas on what to level on and where,
I did at the entrance to the mines just outside CAMP HORIZON, Copperbell Mines. Its a 30 second run from horizon past a few aggro mobs but the mobs in the area don't aggro. Its the place where you talk to the guy to open the dungeon. Nodes spawn in a circle. I'd probably go there earlier another time. You are trying to hit Iron Ore, I ended up with a couple of stacks. Plus about 50 HQ which I am going to turn into HQ ingots if I can when I level Armorer. I got 1 1/2 levels of ARM 11-13 making ingots on quick synthesis. If I could have been bothered I think I could probably level ARM to 20 using those mats.
I decided to check out the leves after turning in my R15 class quest at the miners guild. Collect from the leve guy in the adventurers guild. I had a ton of leves stored. I tried a few leves but the level 10 leve - name has something like fools gold in it - is the best one by a mile. The XP was brilliant. Something like 9000 for hitting the 8 x 6 hit nodes that spawn and another 4000 for each turn in if you hit the max. requirements, every 10 mins. The turn in is at Camp Horizon. You might be able to do this at 10 but you get no ores so that might be gimping yourself on a money making opportunity. At 17 though the XP started dropping off a bit because there seemed to be a drop in the amount of points you could get from the turn in and I could no longer get the 25% bonus. It *might* be worth staying another level as it will make the next bit easier.
I tried to go to the area suggested to collect the rank 20 items ahead of time so they were ready to turn in. 99x Grade 1 carbonised matter Middle La Noscea. BUT its in an area with aggro mobs and when I tried it there was noone clearing them so it sucked, badly. So the solution. Go just outside ALEPORT. There are a bunch of nodes on the run up towards Sastasha dungeon entrance (straight North). Again you can do a circle. 4 nodes were popping regularly. At 17 I was hitting raw Danburite and occasionally popping a buff and getting Sunrise Tellin. I don't yet know if they sell on the AH but I've several stacks of each. One 1/3 stack sold in about 5 mins for 1500G so I expect that it will net upwards of 25k in total if it all sells eventually, nice.
At R20 the class quest really is not worth doing yourself. I have a level 31 Botanist so I used him to grab the 99 Grade 1 Carbonised Matter - Just outside ALEPORT again. Took maybe 10 mins. It would take about 2 hours if you did it in middle La Noscea with miner and all the aggro ****. You could buy them off AH if you have some cash. Be around 10k I think.
Anyway after the class quest I went back to ALEPORT until I hit 21. Objective achieved at this point because the whole reason to do this was to mine silver ore for my GSM and Effervescent Water for my ALC. These are in South Shroud near a small camp along the path not far after you zone into it from Central Shroud, BUSCARRON'S DRUTHERS. At 21 its a bit high. I need to hit 22 for some gear upgrades as I am at 50% on Effervescent water and 37% on Silver ORE at the moment, so 21-22 isn't going well here, might be better to grind out 1 more level at aleport tbh. I expect this to take me well past lvl 25, I might stay here til 30 as the silver ore will probably sell nicely, or craft into ingots with my GSM.
11-15 Copperbell Mines near Camp HORIZON - Iron Ore
15-18 Leves (lvl 10) from Camp Horizon
18-22 Outside ALEPORT - Raw Danburite first then Sunrise Tellin
22+ BUSCARRON'S DRUTHERS (South Shroud) - Effervescent Water then Silver Ore.