This is very true, do not look in crowds. If there are more than 3 people I cannot do more than add small details to conversations at that point. One or Two people I can control the conversation and will steer it to interesting topics.Try looking not in the crowd.
I am typically doing my own thing with very little interest in joining crowds or groups of people... in fact, joining a 'circle' of people is something I am really bad at and never do.
I typically only talk to max 2 people at a time... any more than that and I'm relegated to silent edge-of-crowd observer, unless they are mostly very close friends.
The only thing different I have to add to this, is I smile like a giddy schoolgirl listening to people's conversations. They care about such simple odd things and I find it terribly fascinating.Well, INTJs do not usually hang out in large crowds, and if they actually do, as some of the INTJs mentioned earlier, will stay at the periphery. We generally like to stand from a distance where we can observe happenings. I myself love to do that. It gives me satisfaction being able to understand social interactions between people i know. I assume INTJs don't really like to go out, as I do not go out unless absolutely necessary. We are usually poker faced... Not really adapt with expressions i guess. Lastly, personally I happen to smile in the public sometimes when i notice something funny or weird that I didn't realise all the while. It comes across to my friends as freaky or some sinister plot hatching freak, apparently.
The problem with spotting us; is we don't all act or dress the same. INTJ are the second to last for caring about their appearance, but they understand the value of being presentable. INTJs are likely to dress up nice, but forget to clip their finger nails or comb their hair. If they haven't researched how to make themselves presentable, they will wear practical clothes everywhere.
I used to wear a very light carpenter jean and whatever t-shirt was at the top of my drawer. Now, I have a college jacket that matches my shoe color(The collar also matches my eyes) and some nice dark aeropostale jeans.
Whatever you do don't set yourself too hard on finding an INTJ specifically, I know some pretty terrible INTJs who cannot get their lives figured out. Arrogant, lazy, and negative; find one who is at least willing to develop their Fi and is actively working to better themselves.