always try to have a good posture(back straight,feet flat on the floor) ALWAYS try to have a smile,straight or crooked (straight would be better). try to challenge guys by being mysterious they love being challenged (but dont do it too much u will seem unapprochable) if u r shy try to say hi to him every other day. wanna really get his attention? try being clumsy or ask 4 help, but when u do so and he helps u give him eye contact. just to let u know i used these tips as well and he keeps noticing me!
PS. u probably hear this often but its always good to be yourself whether you are flirting or on a date, if your with him and u r not youself he'll notice more and more that ur a fake so GOOD LUCK!!!