Here are some (not all) key points concerning multiple attackers:
1) Until you reach a high level of finesse in your GC movement, your best bet against multiple attackers will usually be lighting-fast, aggressive preemptive attacks (chops, palms/eye strikes) delivered with rapid STOMPS into each attacker until you can clear space to escape. Don't stay in one place or engaged with one guy for more than a split second. "Pin-ball" between them, striking to kill with each stomp, until you can "make a hole" to escape. Lifting your knees and stomping hard maximizes your balance and ability to move in any direction while making it tough for anyone to get a good hold on your legs. Move in a low fright-reaction-esque position as you explode on the bad guys. If you're not attacking to create space to escape, you're losing.
As you advance in GC, more subtlety will become available to you, especially when dealing with multiples. You will be able to move less yet accomplish more in terms of remaining unavailable to the bad guys while making your strikes unavoidable. You'll be able to move closely around bad guys while manipulating their balance to make them get in each others' way while striking them down. This is very different from the "running around the group" ineffectually that you sometimes see, in that it requires far less movement, making it doable even if you are slower/older/weaker and in confined space.
Of great importance:
1) Do NOT offer any direct resistance to anything. This is how you remain disengaged in order to maintain your freedom of movement.
2) As the action begins, choose one guy on the periphery of the group, attack him and move around him. Don't try to engage several at once or waste time second-guessing whom to go after first. Do not back away from the group once the violence is on--move to the side and in.
3) Remember that because you have GC single-leg balance, you DO NOT have to stop moving or "set" yourself to strike powerfully. As long as at least one foot is on the ground, you can strike effectively in any direction, even while moving.
4) Box stepping and reverse box stepping are critical to being able to cut angles around attackers quickly and efficiently while maintaining balance.. .