Here is some advice to follow if you're arranging an art workshop.
1. Send out a questionnaire to the attendees before getting the art supplies
There might be some workshop activities that you know the attendees will require specific supplies. However, if you're still trying to decide which art activities to include in the workshop, you should send out a questionnaire to those who have booked a place or expressed an interest in the workshop, asking them if they are mediums they're particularly eager to try or specific surfaces (i.e. paper, canvas or wood) that they'd prefer to make their art on. Additionally, you might want to enquire about which brands of colouring pencils, acrylics and other materials they enjoy using or find easiest to work with.
This will ensure that you collect supplies for the workshop that the participants will actually use and that will make it as straightforward as possible for them to create the artistic effects they want on whichever surfaces they select. Furthermore, when the workshop comes to an end, you'll be less likely to be left with surplus pencils or paints that went unused and which you, therefore, need to try to sell to other artists or to store.
2. Ensure there are spare art supplies
It is sensible to keep a handful of, for example, spare paintbrushes, pencils and erasers on hand. If during a life drawing session a workshop participant uses too much pressure when drawing a line with their pencil, it might snap. Likewise, if a person forgets to rinse the oil paint off their brush after completing the first oil-painting seminar, the crispy, paint-coated bristles might break off when they next use it.
In these mentioned instances, being able to grab a spare paintbrush or pencil that is the same as the one they were using will allow the participant to continue making their art in the way that they had been before their tool broke. You can avoid time-consuming options like having to switch to a brush that's bigger, smaller or a different shape to the one they were using, or to a pencil that's a different graphite grade. Switching to a different version of that tool will mean the rest of their brush or pencil work won't match their previous work and the overall look of their art could be spoiled.
If you're arranging an art workshop, work closely with art supplies services to stock up as necessary.