Once your sim is activated, all new sim orders made via your account (Spread giffgaff), including sims you've ordered and handed on to friends will earn you 500 points upon their activation. Points earned in one month will be accumulated and will show on your account around the 5th of the following month. Points can only be claimed/used on the Payback Payout in June and December.
Plus, if you get a new member to activate a sim within 6 weeks of registering your own sim then you'll also receive £5.00 extra credit (added to your account within 24hrs.) for the "First recruit/activation bonus". This is a one off payment for recruiting your first new member. more about the Free Credit You ONLY get the £5 free credit after activation (which by the way includes topping up or buying a goodybag) minimum TOP-UP £10, if you got your sim from a referral link / signature banner or if the person who gave it to you ordered it from their spread giffgaff page. Sims ordered direct from giffgaff (from the website, ebay banner etc) do not attract this bonus.