Something that always seems to come up is the ol' 'what can I do when I'm not at Crossfit?'. A valuable exercise is to practice writing down movements you can do with what you have. Even if you don't have any equipment, I'll bet the list will surprise you.
Here's a start:
Burpees, Pushups, Dips between chairs, Handstand Practice/Pushups, Squats, One Legged Squats, Lunges, Jumping Lunges, Sit ups, Overhead squat with broomstick...
Once you've established what you can do, decide how you're going to do it. A great way to start is pick a benchmark workout that we do and create a variation based on it.
Let's take Jackie
This is esentially a big 'cardio' piece followed by a weightlifting exercise, followed by a bodyweight movement. You might decided on something like this:
75 Burpees Sub for Rowing
50 OverHead Squats with Broomstick Sub for Thrusters
30 Dips between Chairs Sub for pullups
Looks tough! I'm sure you'll get a good workout, even with Jackie's less afluent little sister.
Start a list of things you can do and keep it handy. Even if you can't make it in to Crossfit, you can still stay fit. No Excuses!
Another great idea is to buy a minimal amount of equipment. Here is an example of a great mini home gym. Total investment: Under $100 (get a dumbell instead of a Kettlebell and I'll bet you could do it for under $30). See how many combinations you can come up with using this equipment...