I can help you here.
I spent a great deal of time researching how to make excellent coffee this time last year. I only drink Americano (black) with no sugar, and to really appreciate great coffee this is my first tip,: no milk and definitely no sugar. It will only take a mug or two and you will wonder why you ever polluted your coffee.
There are several factors in making great coffee. Much depends on what you want, espresso, americano, "polluted" etc. Here is a list of what I learned and what I use.
Water: Tap water is often hopeless. However, alternatives can be expensive. The best solution if you can afford it is a reverse osmosis counter top at about £350. This will do all your drinking water as well, and eliminate limescale in kettles, irons, and anything that uses very hot water. Much of this depends on the water in your area. I live in Kent, which is about as bad as it gets. Limescale everywhere, iron from the pipes, it is dreadful. The worse the tap water, the worse your coffee. Never use distilled water. Try to avoid bottled if you can, too much plastic, but if that is your only realistic option, the easiest is Volvic for its mineral content, that is good for coffee.
Temperature should be around 95 Celsius.
NEVER NEVER use supermarket coffee. Buy from small online roasters, who will always print the roasting date. Coffee more than three months since roasting belongs in the bin. It is best to grind your own (see grinders below), but if not, set up a subscription with a small roaster and have your coffee delivered ground. Always state what you want, espresso is a very fine grind, whereas filter is coarser.
You do not need an expensive machine. I use a £20 clever dripper, but that is no good for cappuccino or espresso. For these you will need a machine.
Only buy a machine that makes what you want. Do not waste money on a milk-frother if you want espresso for example
Go onto Youtube, there are several very good videos reviewing coffee machines and makers, how to use them, how to make great coffee and more.
Buy the best grinder you can afford. They go up to over £2,000 which is ridiculous. I have one that cost £300, and it really makes a difference. Cheaper ones will be ok, but do your research.
If you use a machine, learn how to tamp correctly. You want your coffee going through in 30 seconds, give or take.
Scales with a timer are vital if you are making filter or French press
There is a UK coffee forum that is worth a look, but some of the posts are somewhat OCD in regard to the lengths they will go. One example is a spreadsheet detailing the mix of several bottled waters, in percentage ratios, for the best water. No thank you!
I hope this helps.