And the Lord called unto Moses, and spoke unto him [Leviticus/Vayikra 1:1], why does Scripture mention the call before the speech? — The Torah teaches us good manners: a man should not address his neighbour without having first called him. This supports the view of R. Hanina, for R. Hanina said: No man shall speak to his neighbour unless he calls him first to speak to him. Rabbah said: Whence do we know that if a man had said something to his neighbor the latter must not spread the news without the informant’s telling him ‘Go and say it’? From the scriptural text: The Lord spoke to him out of the tent of meeting, lemor [saying*].
— Yoma 4b**
In his book, A Guide to Derech Eretz, Rabbi Saul Wagschal (Southfield, MI: Targum Press/Feldheim, 1993) adds:
This rule [about calling out] appears explicitly in the Shulchan Aruch (Yoreh Deah 246:12): A Rabbi should not be asked questions upon his entering the beis midrash; one may only approach him after he has settled down.
— Wagshal, p.66
There is a more general note on the concept of derekh eretz at My Jewish Learning. There is a great deal of information about the concept of “guarding the tongue” [shmirat ha-lashon] on the internet and in print. I have not found cites to particularly recommend, despite extensive looking; if anyone has good ones to recommend, please suggest them.
The 19th Century author Chofetz Chaim (R. Yisrael Meir Kagan) and the contemporary Joseph Telushkin famously focus on this topic. There was an article written some years back about gender considerations — does the prohibition of “evil speech” [lashon hara] effectively prohibit topics important to inter-personal and communal relationship, i.e., what was understood for centuries as “women’s speech”? — but I can’t locate the citation.
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*Footnote: “Lemor here is taken to mean ‘to say it (to others)’…
**Soncino translation of Babylonian Talmud Tractate Yoma [“the day”], from Seder Mo’ed [appointed seasons]; see Source Materials for citations and more details.
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The “Opening the Book” series was originally presented in cooperation with the independent, cross-community Jewish Study Center and with Kol Isha, an open group that for many years pursued spirituality from a woman’s perspective at Temple Micah (Reform). “A Song Every Day” is an independent blog, however, and all views, mistakes, etc. are the author’s.
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"A Song Every Day" 
In contemplating why Scripture mentions the call before the speech, is this the Lord’s way of telling Moses that the speech is not meant to be considered as a solitary prayer?