How to say Look or Listen so start your phrase

Question

How to say look or listen so start your phrase?

For example as in:

Look, we have to throw a party

Listen, we need to meet tomorrow

Answer 1

Listen, you should be aware that starting a phrase with something like "look" or "listen" is not a good idea in principle. It is rude.

Now, I admit that there are situations in life where this is not so important, and there are a number of expressions in German that are used indeed. However, their use is very specifically attached to certain situations, are let's rather say: certain attitudes of the speaker.

Alle mal herhören, wir müssen jetzt schleunigst die Rettungsboote klarmachen!

(Somebody enters a room full of people and needs urgent attention.)

Achtung, Achtung, hier spricht die Polizei. Sie werden aufgefordert, umgehend den Platz zu verlassen.

(Well, that's obvious)

Hör mal, du kannst doch nicht Plastiktüten in den Bioabfall werfen!

(Private conversation, e.g. with a misbehaving flat mate. The conversation has already a somewhat aggressive tone.)

Schau mal, wenn wir morgen nicht zu Tante Berta fahren, schaffen wir's dieses Jahr gar nicht mehr.

(Private conversation. The person speaking is patronizing by explaining something in a tone making clear that she would expect the other person being aware of this by herself, i.e. something self-evident.)

If you want to use an attention phrase the polite way, you can say.

Verzeihen Sie, der Herr. Dürfte ich Sie einmal bitten, kurz etwas zur Seite zu treten?

Entschuldigung, Thomas, könntest du mal die Musik ein bisschen leiser machen?

Kuck mal, da drüben vögeln zwei Störche!

Tja, weißt du, das habe ich mir zwar auch gedacht, aber letzten Endes, komm, scheiß' drauf!

Note that the latter can be perceived as polite despite the expicite at the end. It is just a talk between friends. The tone is polite because the catch phrase at the beginning is soft.

For your sample sentences I would suggest:

Schau mal, wir müssen eine Party organisieren, sonst ist der Karl beleidigt.

(Again, the person speaking expresses that she thinks that the other person should know that. I don't know if that's the intention of your original phrase.)

Du, hör mal, wir sollten uns morgen mal treffen.

The Du adds politeness. But as commenter Andra remarks correctly: in German it would be more natural to simply say Du for attention seaking, like in:

Du, wir sollten uns morgen treffen.

Answer 2

I have heard "Schau mal, ..." used in this way around here (Berlin), i.e. imperative form of "schauen" + "mal".

"Schau mal, wir müssen eine Party machen"

Answer 3

I am not aware of any direct equivalent of look used as a discourse marker "when we are explaining something or making a point, especially when we are annoyed or speaking very forcefully" (Cambridge Dictionary).

German conveys the aspect of annoyance by other means, maybe by an impersonal passive.

Look, this isn't a debate.
Hier wird nicht diskutiert!

In the following example, special intonation on Herr Müller can be used, with a steep drop between the first and second part. This seems to be the same pattern parents use to address their children when they are about to be reprimanded: Junger Mann! Junge Frau!

Look, Mark, you have been late for work every day this week. Is there a reason?
Herr Müller! Sie sind diese Woche jeden Tag zu spät gekommen. Gibt es dafür einen Grund?