well, here is how i do it...
ever mounth they come out with new free pets at the adoption page. i get aleast 10 or s of each. then wait for them to grow up. if i get dubbles of anything, i put it in a trades group.
i also am always seesing if the pound is open (which it usally isn't) and if there are no pets there that i don't already have, i get one that might be worth something and put it in my trades group (cuz i already have it)
if you keep doing this, you will set up a sizable trades group, and people will want to trade with you more.
i've been here since 2010 or so, so i have a good sized trades group.
oh and one more thing, don't feel shy to be the one to send trades. you need to get your name out there when it comes to trades.
Where i get pets:
Adopton center: they are all free, and new ones come out every mounth
http://www.chickensmoothie.com/adoptables/The Pound: where you can get 1 pet per 24 hours, but it's usally not open.
http://www.chickensmoothie.com/pound.phpTrades: just simply trade with people, and build a trades group
http://www.chickensmoothie.com/trades/tradingcenter.phphope this helped!