Nobody warned me that "bring your documents" meant apostilles, sworn translations, and certified copies of certified copies. How did you get through this without losing your mind (or a fortune)?
Get more certified copies than you think you'll ever need — you'll hand them over and never see them again, repeatedly. Ordering extras up front is far cheaper than going back.
Watch the difference between a sworn/official translator and any translator — some offices only accept the former. I paid twice because I didn't check what was accepted first.
The apostille itself took far longer than I planned for. Start that before you book any appointment that needs it, or you'll be rebooking.
This is a good one to be careful with: exactly which documents need an apostille vs a sworn translation vs a plain copy is country- and document-specific, and it changes. The Documents and Visa sections of your destination guide list what's actually required — worth confirming there before you pay a translator, because the wrong format means doing it twice.
Ordered extra certified copies on this thread's advice — already used two I wouldn't have had. Solid tip.