Good luck! Some tips that helped me when getting inside the SE/30:
1. Be patient. Some of the cables are in tight spaces and it's best not to rush. It's easy to forget and yank on the logic board without having disconnected all the cables.
2. It's easy to bump the video board. Try to avoid doing this.
3. RTFM... at least for some ideas on where things are. http://tim.id.au/laptops/apple/legacy/macintosh_se.30.pdf (Page 39 for Logic Board! It says to discharge the CRT and remove the video board, but... meh... I never do)