You may observe first
You do not have to kiss icons before you understand the practice. If you understand the meaning and want to venerate reverently, you may. If you are uncertain, stand quietly, look at the icon, and ask about it later.
What kissing an icon means
Kissing an icon is a gesture of honor toward Christ, St. Mary, or the saint represented. The kiss is not directed to paint or wood as though those materials were divine. It is a bodily sign of love and remembrance.
Icons confess that the word truly became flesh
Icons are possible because the Son of God became visible in the flesh. The Church does not worship wood, paint, or gold. She honors the person shown, and the honor passes to the prototype.
Many people first learn by watching and asking. A bow, the sign of the Cross, or quiet attention can be a reverent beginning. The aim is understanding and honor, not forced imitation.
If you choose to venerate, do it calmly and respectfully. If you are still learning, stand before the icon and notice who is shown: Christ, St. Mary, the angels, apostles, martyrs, and saints. The icon is teaching the Church’s memory of holy persons alive in Christ.
Understanding should lead the gesture, so quiet reverence is a faithful beginning.