One lie Juliet tells is in the balcony scene, Act 2, Scene 2. She tells Romeo, "although I joy in thee, I have no joy of this contract to-night: It is too rash, too unadvised, too sudden." While it is true that she is hesitant and does think it is too "rash," and "sudden," the fact that she is so easily swayed by him to promise faithful love and promise to marry him proves that the thought of the contract did actually give her joy.
A second lie is that she misleads her family by making them believe that she is going to "shrift," or confession, but actually she is going to Friar Laurence's chambers to be married to Romeo (Act 2, Scene 5). She gives the same lie when she goes to Friar Laurence for counsel on how to get out of her betrothal to Paris in Act 4, Scene 1.
Another lie is that in Act 3, Scene 5 she allows her mother to believe that she is weeping over Tybalt's death and that she "never shall be satisfied with Romeo, till I behold him--dead." In other words, she is allowing her mother to believe that she despises Romeo and wants him killed out of revenge for Tybalt, but the truth in this line is that she will never be happy again until she sees Romeo, period.
Finally, in Act 4, Scene 2 she leads her father to believe that she is willing to do what he commands, has repented of being stubborn, and will marry Paris.