One expects the senior partner to be shown on the left. In the middle of the first century AD the Romans began to use a crown of spikes on the portrait on the dupondius to help distinguish it from the as. By the third century AD, style required most portraits to be busts rather than heads so this is the most common form found on antoniniani. Unlike the dupondii, antoniniani of Caesars show the crown. The laurel wreath and radiate crown was never used.
Hairstyles vary greatly and require comment when useful to distinguish various issues.
Julia Domna antoninianus Diademed Bust Right, on Crescent The 3rd century AD feminine equivalent of the radiate crown was a crescent under the bust. The diadem on the head was often used with the crescent but is not an indication of denomination. Often the emperor was shown in his role as a military leader. Some listings include details rather than lumping all in the term 'military bust'. Like shields, helmets came in many styles and offer great possibilities for variations in description.