I would recommend not limiting yourself.
However, when you Sponsor SFI affiliates, you earn commissions on all their purchases as well. Make sure you are using Great Sponsor tips and ideas and your commissions can steadily grow.
When you refer TripleClicks members, you earn from all their purchases, yet you do not need to provide support as you would for a PSA.
It is really up to whether you are willing to provide support or not.
To SFI Success!
