NOOOO,, do not do it, i did that once, only once tho, cuz i think its best to just be freinds if the girl is a really close freind, i dont know tho its just me,
i asked a girl out that was my freind for a couple of years and she said yeh and it was all cool but she thought it would ruin our freindship cuz relationships tend to do that with people, sometimes