The best way to encourage your affiliates to set up a Standing Order is to have one yourself. Explain to them the importance of a standing order in maintaining their rank and having bonus VP too. One point in having a standing order, which you can tell them, is that they are pre-purchasing products at a lower price which shaves a bit of their expenses that they can use to purchase additional items in case they have to.
Minimize their personal upkeep costs to $30/mo.
Simplify their SFI experience so there are no unpleasant surprises.
Helps to get a jump on and keep them "above the green line" so they can reach their Class Finals