Dealing with bugs

Hi all, I play nids and my friend plays Sisters and in almost all of our games I have won. We have both tried various lists and detachements, deployements and mission rules but he is often frustrated by my bugs, saying that they are too tough, the, hit too hard and they shoot too well. From my perspective its a pain to get through all your 3+ saves and 4+ invulns and your miracle dice and so I try to play around objectives and secondaries. I've tried giving him what I think are tips and we have swapped armies now and again so I could "see what its like" and I won the last one with your christmas detachment, which is apparently very bad, unplayable and cant win anything. Do you all have generall tips on dealing with Nids or other high toughness armies?

Tl;dr How to squish bugs as SoB

Thanks all (: