This is an post that I originally wrote about a year ago, but thought it might be helpful to repost...
So, if I were to try to hug one of our Ward's full-time missionary Elders (no matter how innocent my intentions) it would create an awkward and potentially embarrassing situation for the Elder, who would have to make the choice to reject my hug (potentially offending me) or to have to break the rule because he didn't want to be rude.
I served a full-time mission as a young adult and I can relate to almost all of the items pointed out in the Ten Little Points of Missionary Etiquette article... I actually (jokingly) kept a mental list of all the platonic "hugs" that I got from male investigators, new members, branch presidents, etc. I was very serious about keeping mission rules, but sometimes it was just really awkward to reject something innocent like that from a tearful and well-meaning person (especially an elderly married man) on the day you're getting transferred.
This list isn't meant to make anyone feel bad, especially since many members do some of these things without realizing that they are either #1- against mission rules, or #2- may make the missionary feel uncomfortable. Its just meant to be a list of suggestions of things that you may not have thought about that you can do to help the full-time Elders or Sisters you work with concentrate on their work and spend less time being distracted.
Here is the list that the blog "Mormon Insights" gives, along with my comments added in red font:
1. Don't pay a compliment to one missionary without also paying a compliment to his/her nearby companion. Sometimes one missionary is very charismatic or good-looking and tends to get more attention than his/her companion, so its good to be sensitive to this.
2. When missionaries are paying a visit to your home, try your best to keep the televisions, radios, and computers off. This is so distracting when you're trying to keep the mission rules to not watch TV/movies, etc at all during your missionary service. Imagine if you were trying to avoid sweets and you went to a friend's house who had 100 cupcakes sitting on the table.
3. If missionaries are available to be invited to dinner, keep the visit under an hour. Its hard to leave when members/investigators want you to stay, but missionaries are usually taught to keep visits under an hour and they may have another appointment to get to. Every minute you keep them from their work is a minute that they could be finding someone new to teach.
4. Don't ask missionaries about their girlfriends or boyfriends back home. I know you're curious, but for someone who is trying to concentrate on the work, having people constantly bring up boyfriends/girlfriends can be hard. Especially if that significant other has recently dumped you via letter or email (happens a lot!). Imagine having people constantly bring the subject up when you're just trying to forget it.
5. When conversing with a missionary, try to keep conversations centered on Church-related or service-related issues.
6. Always respect the companionships of missionaries. Do not ask a missionary how well he or she is getting along with the assigned companion. (The missionary leadership will handle that question). Also, if they aren't getting along as a companionship or the missionary really can't stand his/her companion, they probably won't say so anyhow, which puts them in the awkward position of having to pretend that everything is peachy when they'd rather not discuss it with you.
7. Do not ask missionaries how many baptisms they have had. The number of baptisms is not an index of success. This is really an okay thing to wonder about, since we may be curious about how the missionary work is going in our area and throughout the mission. However, there are better ways to find out than to ask "How many baptisms?", which puts the focus on numbers. Here are some other ways you can ask essentially the same thing: "Have you been finding success in the area? (or "How was the work going in your last area?") or "What have been some of your favorite experiences with investigators so far?"
8. Do not expect missionaries to stay in contact with you after they have left an area or even after they have finished their mission service. Some missions have rules about whether missionaries can stay in contact with members in their former areas during the remainder of their missions. It may seem silly, but missionaries do need to focus on serving the members/investigators in their new area, so even if contact is allowed its best to keep it limited.
9. Do not call upon missionaries in Sunday School to provide scriptural support for some obscure doctrine that has been raised in class. The authority of missionaries is in missionary work, not in settling doctrinal debates. Most of the time they know the basics (thats what they study and that's what they are sent to teach), so don't assume that they are doctrinal experts.
10. Do not ask a Sister or an Elder for their first name. The first name is Sister or Elder. Period. I discovered on my mission that a lot of members think its fun to call full-time missionaries by their first name, even if its just in the member's home. They may mean well, seeing themselves as a parent-figure and wanting the missionary to feel a little more normal, but remember that the full-time missionaries go by their title for a reason - it helps them (and us) remember that they are set apart for a sacred mission)