1
Good communication is important.
To sign this, you would first sign 'good' by moving your dominant hand from your chin to your non-dominant hand, then sign 'communication' with the alternating 'C' hands, and finally sign 'important'.
2
We need to improve our communication.
Start by signing 'we' and 'need', then use the sign for 'improve'. Finish the sentence by signing 'our' and then 'communication' using the back-and-forth 'C' handshapes near your mouth.
3
Communication is key to a healthy relationship.
Begin with the sign for 'communication'. Then sign 'key' (or 'important'), followed by 'healthy', and finish with the sign for 'relationship', which also uses a back-and-forth linking motion.