This is a networking event: if I walk up to your clique and you just ignore me, forcing me to stand there until I give up and leave in frustration before you acknowledge my presence and ask who I am, it is not me that is being "rude". It is this kind of isolationist belief that makes it impossible to accumulate groups of people: be charismatic, and make everyone who comes near you get pulled into your conversation; if someone is just standing there, say something to them, don't leave them hanging.
Seriously: this article is dangerously wrong on almost everything it tries to cover (the only parts that are on target are the parts at the end about escape and not being drunk); I only chose that one example because no one else here had complained about it yet, but the real complaint that needs to be made is a general "no, don't listen to this article, there are too many issues with it to cover and the result is you are going to come off creepier".
[time passes as I look at the article again after having looked at the comments here] Actually, no, I also need to pick on these parts, because I'm actively concerned someone will take them to heart:
> A great way to start a conversation with someone you admire (before you say anything about them or their work), is to compliment them on something they’re wearing.
Is the idea that this advice is just for women? Because otherwise, this is absolutely deadly advice: as a man, walking up to a woman at a networking event, talking about something other than work (which is also suggested in this article) and leading with a clothing compliment is not "business networking" and is not going to be appreciated by many women. (And if the person you are approaching is a man, he is going to take it as flirting, frankly whether you are yourself male or female ;P.)
> In every social interaction, one person usually leads with the greeting and the other person goes with it. They have to. If the person you’re meeting goes in for a hug, ...
Now, pair that previous paragraph with this mentality that the person leading a greeting gets to choose its level of intimacy: that a hug is appropriate, and if that's what happens first everyone should be forced to go along with it... this is not OK. To be clear: I'm a "hugger", but I would never greet someone at a business networking event with a hug unless I was trying to be creepy.
I can only imagine how bad the result would be taking this attitude and combining it with the specific advice I complained about in the previous paragraph would be construed. I realize the advice was for the receiver, but without concrete advice for the initiator, I think this gives the wrong impression of the dynamic and will lead to unwelcome situations.
Here's my very simple advice: walk up to people, if in the US (probably elsewhere as well, but customs differ and you should learn the local protocol) hold out your hand for a handshake, say "hello, my name is ____", wait for their name, and then ask "what do you do?" and try to get genuinely interested in their response. Do not introduce yourself with a spiel about yourself: they don't care yet and won't really listen anyway.
Note: while most people will answer this about their job, some people will self-select into more personal hobbies. This is fine, and is the non-creepy way for this to happen, but you are here to business network, so when you've exhausted that topic (and not before, as you don't want to act disinterested) ask them what brings them to the event: this will likely shift them back to their job in a non-awkward way. If they don't talk about a job here, just use this answer in the next section (as it will still be somewhat "functional"). (If they are being actively evasive they probably just don't want to business network with you and the non-"creepy" thing would be to thank them for talking to you and excuse yourself.)
At some point they will feel the need to ask you what you do, as you've now spent so long actually caring about what they do (something that is probably sadly rare as everyone wants to talk about themselves). Now you get to tell them how awesome your job is, and as you already know so much about them you can pitch yourself in a way that they will best understand and that hopefully demonstrates some kind of synergy. This will hopefully cause them to start getting interested in you enough to start asking you follow-up questions.
At the very end of this conversation, you ask them for a card; if they cared about the conversation enough to ever think about contacting you later (and again, this should be due to the business synergy), they will now ask you for a card: you don't need or want some silly excuse for why you are shoving cards at people (as this article suggests), you want to make the other person wish they had your card. If they don't ask you for a card, you "failed", but forcing them to take your card just so they can throw it away later doesn't fix anything.
(I started typing up something about approaching groups, but it got way too complex, and I'm typing on my iPhone ;P.)