Typically when releasing one's zanpakutoh, we see several trends:
1) Specific Action
2) Call out
3) Physical change of Zanpakutoh
1) Specific Action -
While not required, we generally do see some sort of specific action, whether it is merely for theatrics and style or if it actually needs to be done is left to speculation. It can be inferred that this action helps them concentrate and focus their energy to actually REACH OUT to their zanpakutoh and cause its release. As a result, this is not an ability that can normally be done while one is not calm. We do see a couple of cases where this is not the case and someone under emoional duress has released their zanpakutoh, but that is from highly-trained individuals who are prone to such mood swings.
2) Call out -
One thing I see in RP is that Roleplayers love to be wholly unique and creative with Call outs to the point of being utterly ridiculous. On many occasions I have seen entire sentences being spoken, and one time I even saw someone create a call out that took me over fifteen seconds to speak. While I always applaud creativity - THIS IS NOT A SECTION THAT YOU WANT TO BE LONG-WINDED.
When in a battle, you will rarely meet someone who wants to draw it out to very lengthy periods of time because:
1) They want to get on with the fight
2) Their capabilities do not allot them that kind of time
3) They do not want you to reach your full power
Just think about it. If you have to speak an entire sentence, that is more than enough time for an opponent to move in and cut you down while you try to concentrate your energy into the release. The only ones that have used full phrases in both English and Japanese are Kyouraku, Ukitake, and Yamamoto - they are the three most able, most senior and most level-headed individuals in Soul Society. You might be thinking "What about Byakuya?" Well, Kuchiki Byakuya doesn't even come close to them in those aspects, which is why he has only one word.
Here are the typical characteristics that I have seen among all but a half-dozen zanpakutoh among the hundred or so we have seen:
1) One word -
Short and sweet, easy to concentrate on. Think about it. Is it easier to concentrate on ONE WORD, or a sentence consisting of FIVE OR SIX WORDS. To remember something so long is to invite distraction and thus you will not be able to release your zanpakutoh,
2) No Pronouns -
The only zanpakutoh I have seen using a pronoun is Ichimaru Gin when he says in the English Sub "Shoot'em Dead." However, this is a phrase lost in translation. When properly translated it is actually "Shoot to Kill." Thus, in no case do we find a pronoun being used.
Here's why:
A Call out phrase is something to help a Shinigami/Vizard/Arrancar concentrate and something to catch the zanpakutoh spirit's attention. It is not something that is directional. Your zanpakutoh doesn't need to be told who it needs to attack or if it even needs to attack anyone at all. What if you want to merely demonstrate your abilities? Are you going to frighten the hell out of a couple of kids by telling your zanpakutoh to "Crush Them"? That's not practical, not useful and it's poor Roleplay.