Or toss the coin twice, the first toss to decide which side starts face up for the second toss and the second toss to determine the result. If the bias is 60% i

Or toss the coin twice, the first toss to decide which side starts face up for the second toss and the second toss to determine the result. If the bias is 60% in favour of the side intitially facing up on a single toss, then it will have been reduced to 52% for the side facing up on the first of the two tosses with this method. Not perfect but only two tosses are ever needed.