One thing I'd like to throw out there, and really, I'd throw it out to all new builders:
Decide exactly what it is you want your cab to be.
I say this because when we all get introduced to this aspect of the hobby, many times we're enamored by all the possibilities. The thought that "I can play every arcade game, every Atari game, every Nintendo game, every SNES game.... ever made on one machine!!!!1!" is exciting, but realistically not practical. My initial plan for my cabinet was like this. I built a control panel with two 8-ways, a 4 way, a trackball, and a spinner, was quite proud of it... then realized a 37 inch control panel was just too big. So I kept the control panel within the width of the cabinet, tossed the 4-way, loaded all those games and console emulators.... and found that even though I could do all those things, I couldn't do all of them well. I toyed with swappable panels, but ultimately, where was I going to put them when I wasn't using them?
So I took out everything but MAME. Better, but still, the CP was crowded, the 4 way games just didn't play right..... so I built a 4 way vertical only cabinet, I removed the trackball and spinner, pared down the game list, and now my original cabinet plays a multitude of games that I enjoy, and it does it quite well. It's not going to be an "OMG, It plays 40,000 different games!!!!!!!" machine, and honestly, that works great. It's a two-player horizontal cabinet that can play 8 way vertical games. Do I miss playing Tron with my spinner, battop joystick, and regular button? A little, but the control scheme was so awkward that it wasn't the optimal way to do it. I know now that if I want to play Tron, I should look into getting a Tron.
Just a bit of advice. There's no right or wrong way to really do it if you are happy with the end result, but you can save a lot of time and money along the way with careful planning.