Here are some of my random thoughts on this.
You want subs who's work is constantly done in a “workmanlike manner”, who will show up when scheduled and finish on time and on budget.
When you are running a job, it's important that Trade A complete his work (ie Electrician) before Trade B (Drywall crew) arrives a week later, because if that doesn't happen you lose control of time, and time is money (Unforeseen construction delays and cost over runs can throw a project into bankruptcy).
This requires good subs, and if they don't pull the load with this, replace them quickly.
Learn how lien releases work in your locality (it's different all over), get lien releases when you give a check...no lien releases, no check. Get Lien releases from sub/sub contractors also.
Know who is on your jobsite at all times, the trades, the business names.
In many places, Friday at 3 is knockoff time for Beer, make sure they are not having their tailgater parties at your jobsite.
In many places work is allowed to start as soon as the sun creases over the horizon, (just after Dawn), other places have hours to construct specified. Know yours, and explain your wishes to the workmen (not wanting the roofing crew to start at 6am in August, but at noon, might be a no-go for the contractor, so always ask about start and end times).
If you are going to have concrete poured, understand how to slump it, and do so.
And @Jay Hinrichs, do your Mennonite siders ride horse to work (if so any pics).
Just my 2 cents.