every situation is different, the main requirement is to keep within the bounds of Allah as guided by the Quran, the sunnah of Muhammad pbuh and the intellect.
due to the human nature - flaws sometimes occur, therefore the best method is to be as alert as possible when interacting and staying within and coming within the bounds of Allah ASAP.
the safest method is getting one's guardians to do the interaction.
when khadijah (ra) took a liking to the Prophet pbuh she sent a servant to Allah's messenger pbuh to find out how he pbuh felt and then they got their respective guardians to arrange it.
khalid ra once bullied a man and said "man, marry me your daughter!"
bear in mind that taqwa of Allah comes before everything, whether meeting via a matrimonial site, sending a sibling, cousin or friend to set up a line, or speaking in a public place - isn't that easy to see in such a loose and brazen day and age?