Getting them Quiet!!!
Some ideas for getting the girls' attention and getting them to be quiet and LISTEN. If you have already tried the time-honoured raising of the right hand and waiting until everyone has noticed and raised THEIR hand (and shut up chattering) and it STILL hasn't worked, then try some of these..........none are guaranteed, but all are worth a try.
A useful game for Rainbows and Brownies to get them to sit still and listen : call out "stand up tall", "hands on heads", "hands on tails", "hands on toes", "bend down small", "hands on heads" and so on for maybe 30 seconds, then end up with "bottoms on the floor", "hands on knees". But say the last instruction as if it's not the last one, so they're sitting beautifully, waiting for the next instruction, and by the time they realise they're been tricked, you've already started on whatever comes next. It's quick and it works well if you don't do it too often.
If calling out "Guides" or "Rangers" isn't working, try "Rainbows" or "Brownies". They'll get offended so explain that they're behaving like 7 year olds and then they generally look sheepish and behave better (for a while).
If you've only got a few who are consistently bad, try explaining to everyone that you'll all have to wait for A, B, and C to be quiet too. Maybe peer pressure will make them be quiet?
Start a good behaviour candle system, in which you light a candle at the start of every meeting and if someone is badly behaved, it gets blown out and not re-lit till next week. Explain to the girls that when it's burnt right down, the unit can go on a trip/have a party/etc. but make sure you are able to follow through on your promise.
If you've got an egg timer or stopwatch, you can set it on ten minutes at the start of the meeting and tell them that every time you raise your hand you will start it counting down, and stop it when everyone is quiet. Tell them they can play a game at the end for as long as is left on the timer, but again, make sure you can follow through.
Keep them occupied from the moment they arrive : for example, have a table set up with craft ideas - and miscellaneous bits and bobs - and let their imaginations run riot when they first get to Guides, for about 10 - 15 minutes. Then call them to attention for whatever you want them to do next.
Along similar lines, have a game going from the very start, one that they can join in as they arrive : a good one is foursquare which needs only a simple court marking out and a ball.