tips on flirting

so i've been feeling lately like i'm not as attractive as the other girls at my school and i think i'm pretty and i'm skinny and all but i have braces and my cup size is an A and i'm 15 and i'm really ready to start talking to new guys bc the last one didn't go well so any tips on flirting and talking to guys and stuff? please don't say "oh you're too young" or anything just pls help with advice<3