Compliment him: Keep complimenting him but do not flatter. Tell him how you find his voice sexy or how his talks make you smile. Make him feel that he is a beautiful being and see him go marshmallow soft for you. :-P. Take his name: Say his name while talking to him.
How can I flirt with my boyfriend without being obvious?
Make eye contact with him.
This will show that you're engaged and really listening to what he has to say. Listening to him, and showing that you're interested, is an easy way to flirt without making it extremely obvious. Be prepared to make a lot of eye contact, especially if you haven't talked to the guy yet.
Men like being complimented on their appearance, as well as their personality. Nicknames are a great way to express affection and familiarity. "Cutie" or Good-looking" are great nicknames when flirting, while names like "Babe" or "Honey" are better for committed relationships.
In plain language: Men often feel most loved by the women in their lives when their partners hug them, kiss them, smile at them, and explicitly offer gratitude, praise, and words of affection. Men also feel loved and connected through sexuality, often to a greater degree than women do.
Simply be courteous and keep some physical distance between you two whenever you meet. Let him have his space but do let him know you miss him once in a while. Remind him of the fun things you did together before but not anymore. Communicate instead of giving the cold shoulder, hoping to send a message.
Playfully teasing him will make him blush a little from embarrassment. Just don't say anything that's too mean, or else you'll hurt his feelings. Sending flirty, playful messages is a great way to turn him on and make him blush.
If you're not that exceptional at flirting, flirting over text is your save and grace. To put it simply flirting is communication plus sparks. Try and think about how you would normally communicate with someone and add a little something in there. Can even be an emoji.