I came up with this and everyone can thank me later.

TPPR.  

Tension.  

Personality.

Plot.  

Reveal.  


The 4 ingredients to good dialogue.    

You wanna have tension.  

You want your characters to have personality and have actual feelings,  and not be boring one note.  

You want your dialogue to drive the plot forward.

Lastly You want your dialogue to reveal important information about the characters and the story.  


TPPR.

Can't disagree with any of that.

An additional thing is that dialogue needs to be easy on the ear.
And though some people naturally get it right, it can be learned  by reading a lot, and listening.

That's a good nugget, Marty.

I'll thank you later.

I would add tight. (At least, appropriately so for the character, moment.)

Marty, this is in response to your WIP thread which has vanished. I'm not sure if you deleted it or if another MOD did. Either way I spent time giving feedback so I will cheat and put it here, and hope you see it.

I know you've been reading a lot of scripts lately, so I'm guessing you know your excerpt is not quite up to scratch, but you should keep at it. :)

So, here were/are my notes:

If I were you I wouldn't bother with your first exterior slug at all. What purpose does it serve? Think budget.
And your slugline should be capped btw.

Call your character either by his last name or first name, not both in the same passage) - James or Hopkins.

I'd go straight to James knocking at Charlie's front door.

You can give his description at the door -

No need for CAPS mid sentence in your description and no need for the full-stops in between e.g.
mid 30s (not Mid). Maybe add some personality? Suggestion: JAMES, mid 30s, dressed in a tired and stained overcoat, with a hang-dog expression to match, raps on the front door.

Btw, 'donning' is the act of putting clothing on, so it won't work in the context you had.

You have a comma after overcoat, and then capital letters for 'Dodges Pedestrian Traffic'.

(insert apostrophe for Charlie's living room) -

The slug should be INT. CHARLIE'S APARTMENT - LIVING ROOM - DAY (delete the full stop).

You kept to four lines in your descriptive passage (good thing to do when writing a Spec), so well done there.
Why is a medium sized white table all in CAPS? Does it need to be white? Can it just be a coffee table?

Why a sofa and a couch?
Run down paint Peeling
Suggestion:: Rundown, paint peeling off the walls, ancient and threadbare furniture that looks like its been donated from good-will.

How many bags are there on the table?

You repeat the word 'bags' when you could just write something like:
James's eyes light up at the sight of two bulging ziplock bags of oh-so-fresh righteous bush.
(thereby once again adding to the character and personality you've already injected with the 'righteous' description.

My advice would be to start a new para with Charlie on the next line.
Perhaps: Charlie sits cross-legged on the floor opposite. Maybe he rolls his eyes, or sighs while James counts out a few notes, digs into his pocket for the rest in small change?

Again you need to add character and personality.

Use James or Hopkins in description. At the moment you alternate between both names.

50 for this shit? (Fifty not 50). I'd add a question mark.
Have James maybe whistle at the amount, or otherwise voice his disapproval.
And then: Unbelievable.
2 bags of bush. Two, not 2. Spell out numbers in full.

James eyes the bags suspicious.
James eyes the bags suspiciously.
Not suspicious, unless you add a comma.

Fair price if your really down.Should be: you're.
Nothing insane about it friend.
Should be: Nothing insane about it, friend. (Add a comma to address, and then a full stop)
Take it or leave it. (New sentence)

Finally, I'm not really getting those last words of what I assume is dialogue, and you need to format it.

You should post a revamp.
But try to post more. WIP threads are usually for a script that's more than half way there.

Many errors I probably shouldn’t have wrote it quite yet.  I feel like I need to read more before I start writing probably not ready.  Thanks for the feedback.