If you want to refer people, you have to get them to go to the site through your referral link which is going to be:
swagbucks.com/refer/YOUR_USERNAME
Some people also do the surveys for extra SBs, but I don't personally do them.
You're allowed to order two of the same prizes per day and five of the same prizes per month. That essentially means you can get $25 total in $5 gift card increments per month. The $5 gift cards are the best deal (the least SBs per dollar), so if you max out for the month just save for the next month. I don't get the higher amount gift cards unless I have enough saved up to get the $25 in $5 codes + a $50 gift card in the same month.
The SBTV method is more than adequate in getting the five $5 codes in less than a month, so depending on how many gift cards you're content with, messing with the other means of earning SBs might or might not be worth it.