You have beautiful eyes.
AI DE-gli OC-chi bel-LIS-si-mi — stress on 'de-', 'oc-', 'lis-'. 'Bellissimi' has four syllables: bel-LIS-si-mi.
A classic and always effective compliment — specific enough to feel genuine, safe enough for early flirting.
'Hai' = you have. 'Degli occhi' = some eyes (partitive article + noun). 'Bellissimi' = most beautiful (superlative of 'belli'). Italian uses the superlative freely without it sounding excessive — 'bellissimi' is natural and warm.
I tuoi occhi mi fanno perdere la testa.
Your eyes make me lose my head.
More intense — 'perdere la testa' is a vivid Italian expression for being smitten
Non riesco a smettere di guardarti.
I can't stop looking at you.
Bold and direct — only use when you have established some rapport
Hai uno sguardo magnetico.
You have a magnetic gaze.
'Magnetico' is dramatic and poetic — very Italian in its expressiveness
Eye contact is central to Italian flirting — 'lo sguardo' (the gaze) is considered one of the most powerful tools of attraction. Maintaining strong eye contact while giving a compliment is essential; looking away undermines sincerity.