Below are some resources to help you in preparing for Reconciliation.  I pray that they are a help to you on you journey toward holiness.
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6 STEPS FOR A GOOD CONFESSION

• Examine your conscience – what sins have you committed since your last good confession.
• Be sincerely sorry for your sins.
• Confess your sins to the priest.
• Make certain that you confess all your mortal sins and the number of them.
• After your confession, do the penance the priest gives to you.
• Pray daily for the strength to avoid the occasion of sin, especially for those sins you were just absolved from.

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ACT OF CONTRITION

O my God, I am heartily sorry for having offended You, and I detest all my sins because I dread the loss of Heaven and the pains of Hell, but most of all because they offend You, my God, Who are all good and deserving of all my love. I firmly resolve, with the help of Your grace, to confess my sins, to do penance, and to amend my life.
Amen.
Here is link to an examination of conscience  suggested by the bishops to help you prepare for Confession.

Other resources for helping you make a good confession are here and here’s one on the cardinal sins,   what about your relationship with others?