Professional thieves are trying apparently not to stand out: nondescript clothing, cap, collar shirt, hiding half his face, gray jacket, a typical jeans etc. They should absolutely try to blend in, to victims it was very difficult to describe and to identify.
Thieves, as a rule, long sleeves, in which they cleverly hide the knife, sharpened coin, and then the subject of theft. In the hands of the thief is rarely a bag or briefcase, and suitcase. But if it happened, it was most often a stranger.
The thief may issue of flashing a concerned look at their stuff, appraising look on someone else's clothes, pockets.
If the thief has already done its dirty work, it starts quickly, sometimes too hurriedly trying to escape from the scene of the crime. That involuntary conduct should immediately arouse suspicion if your wallet and valuables.
Thieves covertly friendly. All in order to curry favor and complacently called, for example, to watch your stuff while you go to the information Desk of the station.
Some thieves virtuoso speakers. They swing the interlocutor and quietly pull out his wallet.
Beggar or a beggar, with a dejected look on her face begging for money for a ticket (funerals, surgery, bread, etc.), it may be as a professional thief, and his companion who look into your purse when you get the handout and assess how you best "client".