It's all about the coffee grind and the coffee to water ratio!
Actually, there's another dimension. The temperature of the water.
So here's a rough guide to making perfect cafetiere coffee.
1) Ideally, start with freshly roasted beans (less than a month old)
2) Boil the kettle
3) Grind the beans, coarse setting, similar to granulated sugar
4) IMPORTANT - don't let the grounds sit around for more than 15 minutes or so...
5) Depending on your coffee strength preferences, put between 7 and 10 grams of coffee per cup into the cafetiere.
So, if you have a 2 cup cafetiere, that's 14-20 grams of coffee. You'll soon get used to what your desired weight of coffee looks like, or maybe you'll find a special spoon in the kitchen to measure the coffee without the need for weighing it!
6) After the kettle has switched off and the bubbling noise has stopped, pour the water slowly from the kettle into the cafetiere. NOTE - there's a lot of talk about letting the boiled water cool for a bit but we think that the actual process of pouring the boiled water drops the temperature by the right amount so it hits the grounds at just the right temperature. Newton did a bit of work (not on cafetieres - that would have been one hell of a blog) but on water boiling: https://en.wikipedia.org/wiki/Newton%27s_law_of_cooling
7) And now for the science bit. Actually, it's not that scientific. Wait around 4 minutes for the coffee to brew and then squish the squishy thing down slowly and then pour.
Some other factors...
Coarser grinds take longer to brew. Conversely tighter (smaller) grinds take less time to brew.
DON'T reboil water. Always use fresh stuff.
It's usual to see some sediment at the bottom of your coffee cup.
Medium roast coffees work well with cafetiere coffee making. Save the darker roasts for espressos.
If you make your cafetiere coffee well, and consistently, it's a great way to build up your coffee tasting techniques. It's also very smooth and with single origins you can really taste the differences between the coffee roast styles and bean varieties.
Don't be afraid to experiment. Small variances in coffee equipment used means that you have to mess around a bit at the start to get it just right. I spent several years in the coffee dark ages making bad coffee but pretending I liked it.