1) Be careful of cheap printers.
There are a lot of cheap printers on the market today, from both known brands and knock-offs. It's important to be careful when buying them as the companies selling them might be looking to make their profit off of the ink cartridges rather than the printer itself. When buying a printer you should always look at the prices of the ink cartridges and their "life-span".
2) Use the right font.
A few years ago, several American students shocked the world by showing that if their government switched to a thinner font, it could save about 400 million dollars a year. While you won't be able to save that kind of money yourself, using a simple and thin font (like Garamond) can improve your ink usage by about 20%.
3) Use the low-quality setting.
Unless you are printing photos or really small items, there is no need to print in the higher printer settings. You can change this in the print setting after you send a document to the printer, usually under "print properties" or something similar. And unless you really have to use color, printing in black and white is recommended.
4) Use recycled cartridges.
Many shops today offer none-original ink in recycled packs, while some even offer refills if you bring your own empty cartridges. Printer companies claim this might harm your printer, but there is no clear evidence to support that.
5) Try using a refill kit at home.
Some ink cartridges can be refilled with a simple kit you can use at home and it's often very cheap to buy at stores. The big downside of this is the potential mess it might create and the work you will need to do each time you use it. However, if these things don't bother you, it's a pretty cheap way to do things.
6) Keep printing.
Just like your car tells you it is out of gas even before the tank is empty, your printer will tell you it is out of ink even when there is still some left. This means that you can keep on printing, even with a low ink warning. It just means the writing might be a little grayer. It might also help if you just take out the cartridge and put it back in.
7) Save paper.
Printing paper can be just as expensive as ink and you can save a lot of money by printing on both sides of each page. Most modern printers have an automatic option to do so, you just need to turn it on. Take a look at the printer manual to see how it is done.
8) Save room when printing presentations.
If you are printing a PowerPoint presentation, you can put about 4 slides in a page and still read them with ease. This will save you both ink and paper. To do so, just look at the print menu on PowerPoint and change the settings to your liking.
9) Don't print the test paper.
Many printers do a test printing when you turn them on with no real reason. Look at the printer manual to find out how to disable this and only use your ink and paper on what you really need.
If you don't use your printer for a long time, the ink in the bottom of the cartridge can dry out and then the whole cartridge becomes useless. To prevent this just print out a single line of text once a week. I use the same sheet of paper for this every time, with each print just one line under the old one.
11) Wait before turning off your printer.
After a print job is done, the cartridge is returned to a protected and closed part of the printer. If you force it to shut down before it can do that, you risk the ink drying up and maybe even leaking.
12) Only print the final version.
There is no bigger waste than printing something only to discover an error and then having to print it again. It is important to double-check spelling and page layout before you print a document to make sure you won't need to do it again.