Are these good practices?
Let other people say, open source, reply with Free Software, until they say they are the same, and then fire out a stock reply, "They are not, you should say Free Software ..." (for reasons people on this list understand and I won't bother to repeat).
When talking about Free Software let someone else say closed source or copyrighted or professional or something else that is blatantly wrong and then help them see why their phrasing does not work, and the phrase they search for is proprietary software, and it is called this because of the licence you get restricting their freedoms.
We should remember we became as expert as we are in the domain over a long period of time, we can't educate people all in one go, so spread a little every day! ;-) We have the answers, let people question, don't take it as an opportunity to brain dump. Free as in Freedom is a great way to keep them engaged. (See the first start up screen of gNewSense, it was a huge statement and got the focus where it was needed.)
Maybe it is true and if we lead with proprietary software means we are on the back foot in your attack from the off, this of course means that the space is open for our enemy to exploit, therefore lead with our weapon, Free Software, personally it has often be easy for me to start to explain it by saying Free as in Freedom, and to guide this we have four basic rules. For the lay person that is usually enough in one go.