Advice I remember from school, 'read around the subject'.
Not just about the WHF? highest rated equipment but also things like what will suit your listening room. Springy floorboards and joists with a large void underneath could play havoc with floorstanding speakers and/or non-suspended turntable designs unless they are on solid wall mounted supports.
Try and get some background on the history behind a product and it's manufacturer's design principles (if they have any). Think about what you could really live with for the next 2 or 5 or 10 years and what you value most if compromises have to be made. (Compromises always have to be made whatever the budget.)
Match up the manufacturer's values with your own and explore. For instance some manufacturers deliberately build to appeal a traditionalist market or to a valve enthusiast customer base. Some turntable makers adhere to a lightweight, minimalist approach and others add weight and damping wherever possible. Another bunch will stick with a 'floating' sub-chassis design. Very few of them dreamt up these different approaches yesterday or purely on a whim. They all have their merits. Are any of them going to be important for you?
Listen to as many different types of system as possible with an eye to your own room and it's limitations or quirks and your own taste.
What kind of listener are you? Headbanger? Radio 4 drama nut? Someone who wants to join-in and dance, or play air-baton, air-guitar etc? A bit of quiet jazz?
These are all factors too.
Do you, or your partner, care what this stuff looks like? (Some don't, some do.)
Don't be scared to buy the occasional item without listening first. (It's not always possible.) As long as you have the option to return without any complications after trying.