I've mentioned before that I have been in the coffee business for over 30 years and it's also a passion of mine as I have a roaster in my garage and an unlimited access to green coffee from all corners of the planet.
The beans are everything, you can't turn poor coffee into a remarkable espresso.
Try to get the SCA rating for the coffee you are buying. 90+ is called Presidential and the best coffees available but also quite rare, think of them as like your Messi, Maradonna, Pele etc. Most of my coffee is between 85-90 but I do also roast some coffees 80-85 but never below 80.
Union Hand Roasted display the quality scores and offer terrific coffee.
https://unionroasted.com/collections/microlots
For exceptional coffee look out for Gesha (sometimes also spelt Geisha), that is usually a mark of something very special. I also like Honey coffees such as from Nicaragua.
Don't continuously buy from the same roaster, they have their preferences when it comes to origins and roast profiles so you will get some repetition after a while.
Water quality is incredibly important, always try to use filtered water and not straight from the tap.
Most blends (90%+) are just a way of introducing cheap inferior beans, I avoid them completely.
I never buy ground beans as you don't know how old it is, it can be very stale by the time you use it.
I never buy from supermarkets, it's on those shelves for a reason.
Grinding beans to perfection is something for barista competitions and not home coffee, try to buy a bean to cup machine with a generic grind, it will serve you perfectly and removes something that you don't need to stress about.
Don't waste your money buying expensive Jamaican Blue Mountain it's good coffee but nowhere near worth what you will pay, it's a gimmick.
Kopi Luwak is cruel and should be outlawed, it's a stain on the coffee industry
For a great day out head to the London Coffee Festival where you will get to try some amazing coffee and some average too, surprisingly)
https://www.londoncoffeefestival.com/