Get the head torqued down first. Wait about 10-15 minutes before giving them the first 1/4 turn, same for the next. Since you removed the head and the exhaust manifolds together I assumed you'd re-assemble the same way. It's a whole lot easier to install the manifolds with the head on the workbench.

Anyhow, now is when you want to TAKE YOUR TIME. Make sure everything is properly fitted, connected, and tightened. The last thing you need is a CHECK ENGINE light coming on after you've finished. I've seen it happen to experienced techs'. A vacuum line left off is the most common mistake, so double-check everything.