I am a German teacher with some French and therefore I am not as confident with using the TL in French. However I have the luxury at the moment of observing my colleague and Head of French, teaching my class, so I can train myself up in useful classroom phrases. If any of you get the opportunity to do this, even if you are quite happy with the standard of your TL, please do. It is such a fulfilling experience. I have gained so much in terms of TL phrases and also confidence, that I am happily using all I have picked up with other French classes and it is making it much easier for me to keep my lessons almost entirely in French.
The trick is to find some really simple phrases and to use them consistently. I find that less is more and often, rather than barking long winded commands at my classes, I prefer to use short phrases and sometimes single words and gestures;
'On pose les stylos' or simply 'stylos' and gesture for it to be put down
'C'est quoi, la date?' or simply 'la date?' and gesture writing it on the board
'Ouvrez les cahiers' or simply 'les cahiers' and gesture opening a book
If you have good routines and if you are consistent, your learners will quickly catch on.
More on routines later!