How do you make a lot of ISK with minimal effort? The name of the game is station trading. It's not the most exciting part of EVE Online, however if you need to (for example) fund your game time with ISK, station trading is a perfect solution. It requires very limited skills, limited time investment, limited ISK investment. Of course, the more you have of each of these, the more profit you will make. However, in order to start off, you only need very little.
With these skills, and even whilst you're still training, you can start investing your money into items.
Go on the market, and browse for items where the;
Once you've found an item, put up a buy order that's just above the highest buy order available (mark your orders to easily recognize your own, cog in the upper right corner of the market window. Set the amount of items you want to buy to 1.
Now, start searching for more items in order to fill the available orders you have, according to the skills you have trained. Try to invest 75-80% of your starter isk this way, spreading it over your different orders. So, if you start with 100m and you have 20 orders available, spend about 80mil of that on setting up 20 different orders worth 1-8mil each (buy only 1 item at the time). In order to easily check and update your orders, drag all the items you've invested in to the quickbar (next to the browse tab, upper left corner of the market screen).
Now you're set and you can start updating your orders. To keep some sanity and not burn out, don't update your orders 15 times a day, but schedule moments where you can spend 5-20 minutes (depending on the amount of orders you have out) to make sure your buy orders are the highest available. However, the more time you spend, the more profit you'll make.
Once a buy order is filled, you'll see the item in your inventory, put it up for sale right away and set the price just below the current lowest sell order. Once this sells, you've made your first profit.
Let's look at the Centum C-Type Medium Armor Repairer as an example and go by the previously mentioned criteria. At the writing of this guide, this was the market information as available in game;
The lowest sell order is about 80 million ISK, whereas the highest buy order is 70 million ISK. Thus, the margin is 12,5% or 10 million ISK. ✔
On a bad day, this item still trades (bought from sell orders AND sold to buy orders combined) quite well, with never really going below 10 a day. On a good day, it may change hands 40 times. For an item of this value, that's good enough. ✔
On every single day in the price history table, the average price is between 'high' and 'low', usually closer to the 'high' price of a sale that was made on that day. This means that it might be tricky to actually fill the buy order, however once that does happen, it's likely to sell. ✔
The price seems to gradually increase over time, until the last time period. This item looks to be overpriced at the moment, however the risk of losing money on this trade is still low since the highest buy order value (currently 70 million) was surpassed over two weeks ago in the sell order value. On the short term, this item is profitable. When you don't update your orders regularly though, this might be an item to skip over. ✖
You can verify how much competition you have by checking the expiration time on existing buy orders. Orders (almost always) have an expiration time of 90 days, which is refreshed whenever the order is updated. So any order with an expiration time of more than 89 days was updated in the last 24 hours. About 15 other people have updated their buy orders in the last day. This is a relatively high amount of competition, which means that your buy order may be useless within an hour. Unless you update you orders multiple times a day, this is too competitive. ✖
Compared to the amount of buy orders, there are very few sell orders. This means that the price is likely to continue rising in the future, especially considering the fact that the average price of the item (in the history table) is mostly closer to 'high' (a sell order) than 'low' (a buy order). Once you manage to fill a buy order, you will not have too much competition. One could even invest in buying up existing sell orders and relisting them for more. ✔
An example from personal experience
This is the secret of every station trader. With experience and spending time in exploring the market window, you will gain experience and learn how to set up better orders and recognize where to invest in and where not to invest in. If you are skilled in the use of Excel or Google Docs and have some experience in pulling API information from EVE's various online market databases, you can even use spreadsheets or tools to automatically find items that are worth investing in.