Use a magnifying glass to inspect both sides of the leaves, stems, and limbs closely. Try to dislodge any strange appearing bumps with a pin or sharp pencil point. A live scale will often hang by its hair-like mouthparts when dislodged. A shiny spot of honeydew may remain where the scale was attached. If you need further confirmation, take a close look and you'll see legs and antennae attached to the shell.
Soft scales are difficult to control.
The adults can be picked off by hand or with a pair of tweezers. Small populations can be killed using the cotton swab and rubbing alcohol treatment described for mealybugs. Insecticidal soap is effective on the crawlers or young scales. It is less effective against the adult scales. Adult females will lay eggs under their body.