Keep your up!!!! Every time you go to watch a match there is some guy screaming at every fighter to keep their hands up. Of course there is an undeniable validity to the cliche even if it is an over simplification with many exceptions. It expresses the need for awareness and soundness – to protect the most vulnerable part of the in a boxing match – the chin. Similarly in Jiu jitsu. We also also need to keep our hands up at times, but not to defend the chin since there is no striking – it is to defend the – not from the danger of a punch, but from the danger of a STRANGLE. Make sure always to use your hand the entering strangle hand if he is behind you and SAME side if he is in of you. Keeping your hands up in these circumstances can stop small problems becoming big problems. As in boxing, don't over do the “hands up” philosophy – but just as in boxing, don't under do it either – defensive soundness is the core of sensible Jiu jitsu and early neck protection is a big part of that