"Fire without movement is indecisive, Movement without fire is deadly."
Squad are set up into fire teams, heavy weapons and support assets will be in blue team while red team in mainly made up of infantry and grenadiers. The reason for this is that blue team is built to be a support team and should focus on using suppressive fire while red team closes and engages by either flanking (takes longer, more effective and safer for the flanking party) or a frontal assault (faster but much more dangerous).
When moving in hostile zones or when taking fire one team should always be tasked with returning effective fire, while another team manoeuvres to destroy the enemy.
When engaged by infantry, teams with auto-rifles or LMGs/MMGs should suppress return fire while rifle teams move to destroy. This is only a guide and certain situations may require different approaches.
Rule of thumb, the team more effective at suppression should do so while the team more effective at destruction should flank/assault.