Just have another pot on hand if you're doing 5 - 6 ga. batches and only have a 5 ga. kettle
I had my own baptism-by-fire experience with my last batch which is promising to be something I am actually proud of (provided it clears someday)
I did a partial mash, with the idea being 5.5 gallons in the carboy. After a few panicked mathematical "holy crap" moments, I ended up splitting a 6.5 ga. boil between 2 5-gallon kettles, adding equal amounts of the LME and DME in my recipe to both, splitting the hops as well (although I could have been more diligent about the hop additions).
I ended up with about 5 ga. of wort that I topped off with 1/2 ga. of water. OG was 1.08 which was slighty higher than tastybrew said it would be - so I was pleased with the results.