Law and Grace - Which Way Should I Lean?

As a Christian I am rightly concerned about sin, both in myself and in others (hopefully more in myself than in others). On the other hand, Christianity is all about Grace. So when I come to a point where I must choose grace or law, which one should I chose? I can make a wrong choice, based on good intentions, in either Law or Grace. So the question really is this; would I rather err on the side of Law (be too legalistic) or on the side of Grace, appearing to be too tolerant. I know that Grace can cover Law, fulfill Law and even correct Law.