Thanks a lot for taking the time VladCant.
One thing that my friends and I have been arguing a little about is how "real life" a script ought to be. For example, if someone alks into a room to ask another character about something should he say hello in some way or should he get straight to the point. This has always been a problem balancing "real life" and "movie life."
I think the only time you should deviate from "real life" in terms of script writing, is when it is absolutely necessary. Say, you want to provide some background information about the history of a character, but don't want to use a flash back. Maybe you can work that history into a conversation with another character. Maybe one of the characters could be reminiscing. "Remember that time I..." sort of thing. In real life, people probably won't go into monologues reminiscing about their distant past, but if you have no other option, sometimes you have to deviate from "real life" a bit. However, like i said, verisimilitude is extremely important when writing a script. If there IS another, more believable way you can introduce the background history, then use it!
For your example, it really depends. What kind of character is he? Would he say, "Hello, there," every time he entered a room? Is the character the type of character that gets straight to the point? Whichever it may be, you have to have consistency. It wouldn't make sense for a concise character not to get straight to the point. This is ofcourse, very situational. If there is a reason for a concise character not to be concise, it is acceptable. Once again, it brings us back to internal consistency. When writing characters, you should always consider personality traits, the character's history, etc. Then, when you are writing your script, you should have a lot of, "No wait... This character wouldn't say/do that", moments. If you are having these moments, you have done a good job of constructing a consistent character.
Writing your characters is an important part of the overall project. If you do not have clearly defined characters, it is impossible to have consistency. I'm sure I'm going to get shunned for using this as an example, but look at Friends. Each character is a sort of... Archetype. Ross is the geeky romantic, Chandler is the insecure joker, Monica is the OCD mom-type, Joey is the stupid Italian who gets by on his looks, Rachel is the spoiled rich girl, and Phoebe is the superstitious occultist. These characters are VERY clearly defined, and their dialogue and actions clearly represent their characteristics. I'm not saying that your characters should represent some kind of archetype, but looking at them in the WAYS of an archetype makes it easier to write their roles. The more complex a character becomes, the harder it is to write them (which is not necessarily a bad thing).
I'm going to write a short character outline, and try to use it in your example. Bob is a 23 year old construction worker. He still lives with his parents, and is somewhat of a mama's boy. He was never really popular in highschool, and preferred to be with his family and few close friends. Recently, his mother has been diagnosed with a rare disease, treatment for which is very expensive. Given that it is winter, construction has slowed almost to a halt, and Bob is out work. A combination of a worry for his mother's health, and the lack of income, has made Bob exhibit signs of high stress. There is not much time left for his dear mother, and Bob needs a way to make some money quickly. At the start our story, Bob seeks out his best friend Frank for advice.
Bob enters a dimly lit room. In the middle of the room sits Frank, watching Wheel of Fortune on a tiny television set.
How would this conversation start?
"Hey Man! I haven't seen you in like a year What have you been up to? How's law school treating you?"
"Hey! Yeah wow, it really has been like a year. Shit, best friends should see each other more often! Law school's been okay. Although, I have completely forgotten the meaning of a 'good night's sleep'. How are you? Still dating Jenny?"
etc.
OR
"Fuck man, I need some money."
"What's wrong...?"
"My mom. She's really sick man. I'm fucking broke. I need to make some money. Quick."
Of course, it would depend on the relationship of the characters. If they are best friends, a glorified "catch-up" session would probably be outweighed by the importance of the health of Bob's mother. Bob would get straight to the point, knowing that Frank would understand. However, if the characters barely knew each other, Bob might need to ease himself in in order to ask for Frank's help. In either case, consistency, consistency, consistency!
I would also suggest writing characters that are unlike yourself. You don't want to turn script writing into a glorified "What would I do?" game, especially when we are often not completely honest about ourselves.
Sorry for the lengthy and unorganized post. I was just writing things as they came to mind.