I'm not sure if you can use "Please" in a stand-alone context. But you can definitely use it in conjunction with other verbs. Please, in these situations is "請", pronounced qing3. 請幫我 (qing3 bang1 wo3) = Please help me. 請告訴我 (qing3 gao4su4 wo3) = Please tell me. 請便 (qing3 bian4) = Please make yourself comfortable. Thank you is simply. 謝謝 (xie4 xie4). I've been told not to attach a 你 on the end of the phrase by a couple of people, or at least not to do so very often. So I guess say 謝謝你(xie4xie4 ni3) sparingly. Just stick to 謝謝 =P Hope this helps!

please==qing==请 ,请求，拜托 , thank you=xiexie=谢谢

please=qing=请 thank you=xiexie=谢谢

HANK YOU= xie xie ni（谢谢你） Please =请(QING) ，拜托(Bai Tuo)

请qing3 or 拜托bai4 tuo1=please 谢谢xie4 xie4=thanks 谢谢你xie4 xie4 ni3=thank you