Every GLO product has its own directions, so the best place to start is the product label or individual product guide.
As a general rule:
Cleanse your skin.
Apply treatment products such as serums or masks.
Apply moisturizer.
Use SPF in the morning.
For body products, apply them to clean skin according to the product's directions.
Don't use more product than recommended. More isn't always better, especially when you're introducing exfoliating or treatment products into your routine.