It depends on personal preference, but in a slightly formal situation you would say something like I got you a present, here you are. and then if they said something like 'no, I can't accept it, it's too much' you would then say, 'Please take it.' 'Here you are' is to draw attention to the fact you are giving them something. 'Please take it' is asking them to accept your gift. Another common way of giving someone something is just to say 'This is for you' and then give it to them or if it's between friends 'I got you something' or 'here you go' are fine aswell. They'll all be understood.