Se identifies the sentence as a question. If you use it with a statement X that contains no question words, it means "Is X the case?" This is the normal way to ask a yes-no question. For other questions, se is optional but can improve clarity. See The Most Important Derivational Suffixes.

He identifies the sentence as a command. This is usually necessary—how else will your listener know? If it appears in a sentence X, it means "You, make it so that X is true." In a command, it often makes sense to leave out the divider; commands often mention only known referents.

Ao identifies the sentence as a proposal, a suggestion, or an alternative. It can mean "let's", as in "let's go bowling", or "one possibility is...".

Ep negates the sentence. It changes "X is the case" to "X is not the case".

The unmarked position for a sentence modifier is at the end of the sentence. Remember that the end of the sentence is the most emphatic position. If you put a sentence modifier at the beginning of the sentence, you are muffling its meaning, saying that it is relatively unimportant.

Pa ufaa ep.
Belief actual+same not.
That's not true.

Ep pa ufaa.
Not belief actual+same.
That's not really true.

If you put a sentence modifier in the middle of the sentence, you are saying that the part of the sentence before the modifier is somehow "more responsible" for the modifier than the part after. (This is something of a reversal from the usual rule of thumb, but it makes sense because moving the modifier implies that something is special.)

Tiha gageun ao.
Change-location+action park+change-to proposal.
Let's go to the park.

Tiha ao gageun.
Change-location+action proposal park+change-to.
Let's go somewhere, like the park.

Uan tags a sentence as an observation, similar to English "isn't it?"

Ala means that the sentence's truth should be clear, similarly to "obviously" or "of course".

Ui emphasizes that the sentence is true, strengthening the claim of the sentence. It is similar to English "really" or even to the punctuation mark "!".

Api weakens the claim of the sentence. From a formal, logical point of view it has no meaning, but pragmatically it reduces the emphasis placed on the sentence, perhaps out of regard for someone's feelings.

A discourse connective can be placed anywhere. It indicates a relation that holds between preceding discourse and following discourse. How much preceding and following discourse is left wholly to context—a discourse connective may hold between two words of the same sentence, or between two chapters of a long document.

Ataha says that following discourse offers a generalization of something more specific that has been mentioned.

Leu says the opposite, that following discourse offers a more specific example of the general topic of discussion.

Iuk says that following discourse is in some sense logically or chronologically before preceding discourse. It may mean "because" or "before that".

Hapa says that following discourse is in some sense logically or chronologically after preceding discourse. It may mean "therefore" or "after then".

Iae says that following discourse adds more weight to an ongoing line of argument.

Co says that following discourse contrasts with previous discourse in some way. It's similar to "but" or "however" in English.

A conversation management word often makes sense as the first word of a sentence, or even as the only word. Like other floating particles, it can of course be used anywhere.

Lit and lut express greeting and parting. They can also be used to mark the entry or exit of a person from the conversation or from a temporary social group.

Tin and tun express gratitude and regret. Tun always means "I'm sorry about that", never "I'm sorry for you" (that's pity, not regret).

Teti is for calling attention to yourself. (For calling attention to something particular that you're saying, see the emphasis derivational suffixes in the dictionary, such as -cua-.)

La expresses confusion. That's why you use it when you forget the words to a song.

Ee indicates hesitation. You are holding the floor until you can figure out what to say. You can draw out the long vowel as long as necessary.

Poe says that you've heard and understood what you were told.

Poua is similar to "roger wilco"; it means you've understood and will comply. You may be obeying a command or only agreeing to a suggestion.

Exclamations, like the conversation management words, can be used anywhere and make sense by themselves, as the only word in a sentence. In fact, the division between the categories could be seen as arbitrary.

Tat expresses surprise or sudden observation.

Uku expresses worry, or a troubling observation.

Hii expresses awe or respect.

Ce expresses joy or triumph. Since it's short and sharp, say it several times if you like!

Ce ce ce!
Woohoo!

So expresses fear or observes danger.

Ot expresses disgust.