Never underestimate the offensive capabilities of your enemies.
The best way to do that is to never estimate the offensive capabilities of your enemies. Send the thief in to find out first.
R2-D2: Right, my dreadnought should be just around this corner somewhere.
GM: Make a Spot roll.
R2-D2: Oooh, I'm so excited!
R2-D2: 6. Well that should be plenty with the size modifier.
GM: You see only the dim walls of the desert canyon, echoing with the protesting whine of your servos.
R2-D2: Oh god, don't tell me it's been buried by a sandstorm. This is totally going to suck.
GM: Suddenly, a small figure leaps out and <roll>... shoots you!
R2-D2: Oh phew. I was worried there for a second.
R2-D2: Dodge: 10. Do your worst, primitive desert projectile weapon. Is it a sling shot or can they afford a potato gun?
GM: <roll> Sparks short out your circuits. You fall to the ground with a thud, paralysed.
Jawa: Huh. An outdated model. Might be worth a few quid.
R2-D2: Come over here! I'll pull your arms out of their sockets!