I have two major rules with old builds:
1) I try to use a CRT monitor if possible.
Why? It's mostly because all of my older *somewhat* period correct LCDs either are dropping like dead flies or suffer from various problems such as poor upscaling. LCDs unlike CRTs need to upscale any resolution lower than their native res. unfortunately, not all LCDs are created equal, so some will do a great job at upscaling and others might poorly scale the picture and massacre the image quality. (my Fujitsu B17-2 falls into the "piss poor scaling" category, while my NEC MultiSync LCD isn't too bad when it comes to scaling. Probably in the same league as my Eizo L557).
2) Try to use original storage medium, again if possible.
Why? Mostly for the true retro experience, though if truly there isn't any alternative, I'm open to trying modern solutions (even though I'm a bit reluctant on this). Network storage, however, is the sole exception. Truly it's a godsend when you're tight on data storage space you just offload the big files to a network drive and call it a day.
Other guidelines in no particular order:
-Use a dedicated controller with its own BIOS if the on-board controller is fussy or have limitations (such as AwardBIOS' 32gb limit or the CMD640 controller's bug)
-Network card is always a plus (see #2), bonus kudos if it can do network booting (PxE or NBP)
-Try to find and use alternative BIOSes if wanted (such as Microid Research's MR-BIOS)
-Prefer ISA soundcards instead of PCI ones if your mobo doesn't have a PC/PCI (SB-Link) header and that your mobo has a ISA slot.
Proud owner of a Shuttle HOT-555A 430VX motherboard and two wonderful retro laptops, namely a Compaq Armada 1700 [nonfunctional] and a HP Omnibook XE3-GC [fully working :p]