A large portion of habitually successful trading and crafting happens outside the physical act of trading itself. There are some ways in which this is glaringly obvious (checking the trade site, poe.ninja, checking crafting percentages on craftofexile, reading forums etc.)-- that is not what I want to cover here.
Instead, I want to focus on the systems and behaviours that you can adapt or build towards that will have a huge positive impact on your profitability in the long run, as well as ease some of the "friction" that is so caked into the economic activities in the game today.
It does not matter if this a guild, a discord, a global channel, a forum, or a friends list. There is no economy without player interaction-- and much like the life expectancy of a human being living in isolation is dramatically lower than that of one living in a community-- our ability to generate currency suffers without any type of support system. There are benefits psychologically to having a like-minded peer group who can help support your ideas and foster a sense of belonging/purpose-- this on a motivational level is worth it in of itself-- however, the primary benefit within the context of this website is that you have access to capital in times of low liquidity or when economies of scale play a huge factor. Being able to have someone you can run ideas by who can provide feedback, or help you split farm is additionally useful-- but there are few greater annoyances when actively participating in the market than seeing an item (a very valuable synth base for example) get posted for far less than its potential value and knowing the window to purchase it is very small, but you just spent 300 divines on a Mageblood and have no raw currency on you, despite the fact that you could easily sell some items to afford it. Having a trusted peer that can loan you money in situations like this is invaluable. Building this trust with someone can take time, but it is worth it. Always pay these people back. Always reciprocate if you are able. The long term value of a network is worth more than any single item is. Do not sacrifice your integrity with these people. I will elaborate on the benefits of economies of scale in its own section- but in short-- probability x material cost = average cost to craft / create-- The sale price of items is often severely out of line with these figures on a cost accounting basis -- especially if there is a uncommon technique being used--- to offset variance in small sample sizes-- bulk crafting/attempts can create a much more accountable /reliable expectation of return. This can get expensive, having a network to offset this is huge-- especially when you also consider the time that can be saved by division of labour, especially if different skillsets can be used (a delver, a heist runner, a crafter, one guy who buys essences, a harvest farmer, one who buys div cards etc.--- an individual can do these all themself, but will take far longer and cost far more as you will likely temporarily spike the price of a supply market / have to pay a premium to bulk buy)
This section doesn't need much explanation. I recommend 10 tabs at least. I have 80 (and 1800 in standard , lol) The more items you can have for sale, the more market exposure you have and the less discerning you have to be about what you can keep or not. There have been countless times I have sold complete garbage items simply because nobody else had them, and the buyer was frustrated with looking. Knowing an item is decent and probably has some use case-- but knowing that its note worth price checking is a non issue if you have dump tabs at certain values, if items rot in them- lower the tab cost once every few days. Having access to bases, random uniques, influence mods , flasks etc. that you might otherwise have to go out and buy has a huge benefit as well in easing "friction" and as a matter of opportunity cost / time.
Third party applications are a fairly ubiquitous part of PoE. They are useful tools. Use them to inform your decision making process, but do not allow them to be the sole factor. Many have flaws in design, and some are easy to "cheese" (pricefixing with awakened trade, PoE.ninja sales reporting is often outdated, dont get me started on TFT)--- experience will subconsciously steer you towards better decision making-- but self reliance and having a raison d'etre for your economic decisions will force you to actually learn and understand why you should or should not do something, this approach if habituated will build upon itself -- and the knowledge gap is massive in this game, there are few greater investments you can make than understanding the why-- the how is reactive-- the why is proactive. Become the fisherman.
If you have a stance on something, have a reason why. Citing a streamer, YouTube video, Reddit post, or soundbite that you've heard regurgitated is not a reason. It's intellectually lazy and it will severely harm you in a multitude of ways in the long run. First, any strategy you hear about is inherently sub-optimal, as you cannot be first to market and if you are hearing about it- someone else probably is too. Second, long held notions become conventional wisdom. These tidbits of wisdom may seem like universal truths - but their mass adoption took time- and often, in that period- whatever truth they may have held has likely shifted into the gray as the game has evolved. Furthermore, conventional wisdom cannot logically produce anything outside conventional results. If you want to excel you will need to be an outlier. It is very cliche, but I am reminded of the Mark Twain quote:
"It ain't what you don't know that gets you into trouble, It's what you know for sure that just ain't so"
But I digress...
The best way to remedy this is to discover opportunities yourself. There is a degree of this that comes from time played and experience, as you build upon past knowledge--- but it is not exclusively available by that means- alot can be learned in a short time by getting out there and crafting, trying new things, builds , archetypes, and "currency/flipping strategies" . This will inevitably lead to some failures. Try to see past those, as they will be your best teachers. Persevering through failure is what will cause your success. Don't doubt yourself. You are learning, and that investment into self will yield far greater long term results than ANY method of farming, crafting, flipping etc.-- even if the early phases are rough or seem slow relative to what you see others doing.
Test your assumptions. Be open minded. Try to always be learning. A differing opinion isnt always a point of contention, but an opportunity to understand the other. This is important. Reddit is to currency acquisition in Path of Exile what WallStreetBets is to money in capital markets- do not mistake an upvote as a measure of validity and gauge sentiment with a grain of salt. Content creators, in particular those that do so on Youtube or any non-live platform have a conflict of interest with your self reliance-- a learned sense of helplessness provides them with a long term "client" -- and while videos can be useful for posterity sake, rarely do they hold weight over time. Its also MUCH easier to fabricate results with editing, ideal setups, and offscreen manipulation---Streams are better for this, but should also be approached with cautious optimism/skepticism. Nobody understands everything in this game. Nobody is ever right all the time. Never trust someone who has an authoritative opinion on every topic, or that always agrees with you. Consider what you watch/read/hear-- but confirm assertions as best you are able before blindly acting. There are many well-intentioned fools.