Can't really write a guide, since I terrible at making money, however here's the things I do when I need gold.
Ciar Adv for 2/3 with Party Quests. Since we're allowed 2 alts it makes this easier, but you could just as easily bring a friend for Adv for 2. I'd recommend running Adv for 3 with an Unrestricted Pass (30k from Shyla) as this dungeon has 2 Golems at the end. Why is that important? Those Golems drop Stamp burns, which can be sold for 150k very quickly, or more if you're patient. The party quests give 20-24k for each member, which is quite nice as it covers the cost of your pass in the first run and then pots in subsequent runs. Additionally, the Green Snakes in here like to drop Fine and Finest Leathers; which are easily 10k each right now for fines, and 12k for finest, each.
After your first run, Adv for 2 is shorter and it's easier to find one person to run with. Two people at 150-200 should theoretically be able to run this, Bug Bears might suck a little, but just camp a corner and windmill spam if necessary.
Grind for Color burns, as these can sell for 100k. Easy missions that reward them are: Defeat the Shadow Warrior on Int and above (Total 100+), Defeat the Fomor Commander 1 on any difficulty.
These are the easiest missions that can give it, but there are others. Shadow Warrior is recommended as it's a cakewalk, but of course you need to be over total 100.
Spam Blood in the Water Intermediate. Can be tricky as the mobs do high damage and the boss is a nightmare at lower levels. But with decent Lucky Finishes and ~5 mins per run, you can easily make 500k-1m in 2 hours, which is one 2x combat exp potion (60k from Shyla).
Buy Gacha and hope. 50 Red coins for 2. Don't do this unless you already have enough pets. And bear in mind that Red coins can also be sold for about 3.5k each.
Keep an eye on party chat channel. See what people are actively buying and wiki to see where it comes from. Think you can handle it? Go for it.
Holy Waters! 15k per stack doesn't sound amazing, but when you're at the point of getting 10 per job, and you can do Heulfryn and Kristell in one day, you can easily build up a nice reserve to sell at a weekend. But to be honest, I only do this when I'm semi afk, and I sit at Endelyon in Tir as her job is easy.
When I am famous, you shall receive the fruit of my labour.