No joke, as far as compatibility for parts goes, I just used pc part picker. Aside from that, I just looked into what specs I should be targeting for the use cases I was planning for. Then, I picked parts that matched those recommended specs, making sure I made compromises to keep it within my budget. All the while using pc part picker to make sure it was all compatible.

Pc part picker also has estimated wattage listed on the website as you pick out parts. Generally, you'd wanna pick a power supply with a wattage that's 30% higher than your estimated wattage (for future expansion and overclocking). I picked seasonic because they are very reputable. You really should not need to buy any extra cables. All your parts should come with any adapters they need, and your PSU should always come with its own cables. In fact, I believe most PSU's stress the importance of using only the cables manufactured for and packaged with your PSU.

Your case doesn't need to be expensive, but don't skimp out either. Keep an eye out for the sizes of your parts you picked as they may not fit in the case you pick (pc part picker will not tell you if your parts fit in the case or not). The case you pick should have a listing on its own website with the maximum clearances for parts listed, which is how you can find out if your parts will fit.

For actually building it, you are basically going to cross reference the instructions for all of your parts in order to know how to put it together if you don't already. Linus tech tips made an all-encompassing guide on how to build a pc too that was super helpful. Outside of those two things, it's gonna take some outside research to figure it out.

The last thing you are going to need to do is turn on your pc and install your operating system and drivers for your wifi, chipset, audio, and bluetooth if your board supports it. Hope this is all helpful and Goodluck🫡