I don't think you really did research, as you can find tons of arcade cabinet plans online (
https://goo.gl/5BoFjz). But ok:
Classic cabinet plans: http://jakobud.com/cabinetPlans.phpCheck
https://goo.gl/ckkqSq for inspiration.
Hardware:XXX-in-1 board, PC or Raspberry Pi. Most people will say go with a PC. An old and free/cheap PC can emulate quite a lot and pretty good. Software side of a PC is not that easy though. Raspberry Pi with RetroPie is very easy to setup, but some people think it doesn't emulate that well. Others (most?) won't notice. No experience myself with the XXX-in-1 boards, but you are limited in the number and choice of games. Also I read quite some bad stuff about these boards.
Software:Depends on the choice of hardware. PC: emulators + frontend. Raspberry Pi: RetroPie or Lakka or Recalbox.
Controls:Don't cheap out on controls. So don't get those packages they sell on eBay or Amazon. Go to a dedicated Arcade webshop (Ultimarc, GroovyGameGear, Paradise Arcade Shop, etc.) and get quality. Some games need an 8 way joystick, some 4-way. Get a joystick that you can change from 4- to 8-way (servo-stik, mag-stik, Ultrastik360, etc.) or get a dedicated 4-way and 2 (depending on the games you want to play) 8-ways. For buttons make a choice between concave or convex. Depending where you come from you might have a preference (f.i. concave was the standard in the US I believe).
Monitor:CRT is more original, LCD allows for a slimmer cabinet. CRT has scanlines, for LCD you should get scanlines through hardware (scanline generator) or software for a more authentic view.
Side art:Make sure to not cheap out on the outside of your cabinet and get yourself some decent side art + marquee. You can get it printed or ordered somewhere. Won't cost too much, but makes a big difference.
Coin door:For the ultimate original feeling, get a coin door. Looks great!