How do you know when a person is preaching upon the sunnah?

[dkSadiq.ibn.Owodunni]

wa 'alaikumus-salaam wa rahmatullaahi wa barakaatuh brother,

BaarakAllaahu feek, a very important question indeed especially in these days where the speakers claiming to be upon the sunnah have become many.

Alhamdulillaah, below are two links to an audio lecture and an article - both by Shaykh Ahmad Baazmool, may Allaah preserve & reward him. In both, he discusses the importance of being careful of the person one studies the Deen from and mentions some ways to know about a person as well as some other very important issues/principles for the Salafi to know in his path of seeking knowledge. Inshaa'Allaah they should be of much help in answering your question.

Audio: Be Careful Who You Take Your Deen From! (scroll down the page for the download link)
http://www.troid.ca/index.php/news/s...your-deen-from

Do Not Put Someone Forward Until You Know What He is Upon Shaykh Ahmad Ibn ’Umar Baazmool
http://www.salafitalk.com/threads/39...hat-He-is-Upon

Here's an excerpt from the article:

"... That which is obligatory upon you, O student of knowledge, just as preceded, is to ask about the condition of this Shaykh and to be sure that he is Salafee. Also what is obligatory upon you in times of fitnah, is not to cling zealously to your Shaykh or whoever is upon opposite of what he sees, but rather you must keep quiet and look to the statements of the major Scholars. Now you find the youth dividing in every fitnah. What is the reason? The reason is them indulging in that which does not concern them and what they are not capable of, so they become divided, fight one another and then lose one another. However, if they remain quiet and stick to the major Scholars, by Allaah, the fitnah would be less. Also if they tread upon the manhaj of the Salaf, that the small students of knowledge tread behind the major Scholars, the fitnah would be less. ..."