In store
The sure way to treat this is some light window shopping at your local electronics store.
Micro Center has been a pillar in recent years when it comes to custom Computer building and has fantastic customer service.
This store specifically has knolegble employees that can provide in depth explinations about each and every part you need for your computer.
They also have a very large selection of brands, makes, models and real time builds within the store itself.
The next best option is Best buy if you do not have a Micro Center within your city. Best buy is a larger company that has also had a deeper
footprint within tech stores within the US specifically. Their selection within stores are not as wide of range but still having employees to help and
ask for an aditional opinion is always a bonus
Online
Online shopping is very self-explanitory. Most parts will be sold online for delivery or pickup no matter where you are located within the globe. This makes it easier for those who especially do not have an electronic store close or even accessible. This option also provides the more obvious deals when making purchases Online.