If you really want to make money by farming, use this benchmark spreadsheet by Peureki.3647 as a reference. They now also have a website at https://www.peuresearchcenter.com/index.html! Use the info tab, along with the individual zone tabs, to learn more about the process. Here’s another website from the [fast] guild in EU. They also have a FAQ section that will help a lot, in additional to a tab that shows what level you should open containers at, so don’t skip out on it. Of course, there’s also trading post flipping and attempting to get valuable rare drops.
I’ll admit that it’s not really my cup of tea to farm stuff, but you might find it enjoyable! If you don't own the expansions, The Silverwastes meta (RIBA) is fairly popular and can be kind of fun/relaxing every once in a while. Check out Hertz’s guide for more info how how this works. Currently you’ll want a bag-opener at level 59/60 to maximize profit (reference). For more details on which containers/bags should be opened at what level, please reference this. There are sections for different bags on the left-panel.
For materials, here’s a handy guide to permanent nodes on gw2efficiency. I will add that there is a rich quartz node at Destiny’s Gorge [&BJMKAAA=] waypoint in Crystal Oasis. You’ll need to take a springer up to the top of the mine to access it. Since it’s a rich node, it’s based per character so you can park multiple characters there at a time.
Since Drizzlewood Coast is currently the hot spot for making gold in the open world, here's a guide on how to get there without starting story and without using Teleport to Friend. This is of course assuming you own The Icebrood Saga Episode 3 or 4, which gives you access to the map:
Head to the Eye of the North waypoint. Everyone has this unlocked as long as you own Path of Fire. You may paste this waypoint code in your chat to link it: [&BAkMAAA=]
Enter the big pink portal in the middle of the room.
Select the Cold War strike mission (squad)
Once you load in, turn around and exit through the blue portal. It should ask you if you want to exit to Drizzlewood - select yes.
Once in, make sure to use LFG to find a squad that's on a fresh map (as in, nothing has been taking yet and all the territories are red). Remember that you can click on the parachute icons on the map to airdrop into those areas to quickly traverse the map. And most importantly, speak with a Quaestor npc to send your commendations to the most profitable legion.