I think the concepts can be applied to both ONS and non-ONS but many of the concepts are written and intended for people who can't pull off a ONS.
Personally I think you should have a ONS seduction technique and use at least the beginning of that even when you are looking for a LTR. If you engage her initial interest and don't try to number close her she will still be interested and intrigued especially if you are confident.
For ONS
Appearance
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Dress the part - this will mean something different for each person but dress is very important.
Hygiene
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Taken care of hair, skin, nails, and the like show how clean you are.
Confidence
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Display confidence just as this site describes including eye contact (very powerful)
Be interesting in a non verbal/non conversational way
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In a night club environment this means you dance and do so while appearing to be fun to be with and not like an idiot.
These are the most important in my opinion; everything below is only second to above. On almost any given night when I am out I have girls try to pick me up or hit on me and it is not because of anything below, it is because of what is above because up to this point they have never spoken with me. You should have a look, walk, attitude that makes the women want to jump your bones. You should not be able to walk past a group of girls without turning some heads. To know if you are doing this or not you may need to bring friends along so they can tell you, when I am out I have no clue this is happening because girls are so subtle about it.
Gauge interests level
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Be sure you can gauge interest levels. Sometimes the interest may appear to be high but it isn't ONS high. Sometimes the interest could appear low but it only appears low because she wants to maintain a certain impression with her friends around, when they leave she will let the hair down.
You need to be able to converse enough with her to get the hints and many will be subtle. If she is just enjoying your company for the moment that won't do you much good when the club closes for example.
Next and don't waste time
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If you are out and about it is good to make a friend or so in the various crowds of interest. Be the guy that when you come by they want you with their crowd and you are welcome there. Make your rounds as you are having a good time but be sure you converse with people, guys and girls alike.
When you next ladies you don't write them off but they are not the focus of your current efforts. You may just mention you will be around amd maybe you'll see them later.
In some cases you have to tell a girl no. In these cases you may need to be a little stronger worded then above. If the girl is not your type, too fat, too ugly, too dirty, too whatever you should depart but use words that are friendly enough that you can still be in her crowd as her friend. Be careful you don't slam the girl as you might be surprised that some of the girls you do like are good friends with her.
Always be a gentlemen but using a statement like - "well I'm going to dance have fun and nice chatting with you" leaves no room for you to be together later and no hint that you like her but is still polite. Whereas "I'll back in a bit will you still be here?" is much more suggestive. Of course if she is your target try "You want to come with me and (get a drink/dance)?" Is much more to the point and shows your interest level.
Show her a good time but don't spend too much time with her unless you start getting some hint that you are getting some.
I cannot think of a ONS I have had where some hint wasn't dropped earlier in the night. The only time a hint wasn't dropped was when before I was ready to next she said "Let's get out of here."
I can think of many instances where no hint was dropped of what we would be doing later but she should have been nexted.
