Repentance means turning away from all that Allah The Almighty hates, to all that He loves - inwardly and outwardly. It entails shunning sins out of fear of Allah The Almighty, realizing the ugliness of sins; regretting the sin and determining not to commit it again. It is to return to Allah The Almighty in humility, fear and hope for the rest of one's life.

Repentance is:

A form of obedience.
A reason for your success in this life and the Hereafter.
A reason for gaining the love of Allah The Almighty and there is no happiness more than the one which occurs by knowing that your Lord loves you when repent.
A reason for entering Paradise and being saved from Hell. Is there any other objective one would seek to achieve better than entering Paradise?
A reason for receiving rain, increase of strength and gaining children and wealth.
A reason for forgiving sins and switching them into reward.
Thus, do not oppress yourself and deprive yourself from gaining the pleasure and acceptance of Allah and make haste to repent.
Many people want to repent upon realizing that happiness does not lie in following ones desires and lusts or committing sins. However, you might not know the way to repentance, or how to start.

Some actions which will help you repent:

Be sincere in your intention, and truthful in your repentance, because Allah The Almighty would then help you and keep away from you obstacles which might hinder you from repenting. Allah The Almighty Says (what means): {Thus it was, that We might turn away from him evil and illegal sexual intercourse. Surely, he was one of Our chosen (guided) slaves.} [Quran 14:24]
Hold yourself accountable for your actions because self-reproach encourages you to do good, helps you refrain from evil and helps you make up for what has passed.
Remind yourself frequently of the consequences of sins and evil deeds in this world and the Hereafter.
Admonish your soul, warning it of the impending punishment, and saying to it: Repent before you die for death comes suddenly.
Remind yourself with the death of people you may have known, and remembering that you will meet death regardless what you do. Don’t you fear that the angel of death would come to you while you are committing a sin? Will regret do you any good then? Will crying and sorrow be of any benefit to you?
Stay away from places of sin and heedlessness because staying away from such places help you repent.
Stay away from bad company, because you will be affected by their habits, and know that they will not leave you alone as long as you are in their company.
Consider making drastic changes to your lifestyle if something in your everyday routine triggers acts of disobedience or negligence to your obligations. You could change your telephone number, your residence if possible, or the commute you use to work or your everyday chores.
Remember the evil consequence of sinning, because this will help you shun sins initially, and then repent from them.
Remind yourself of Paradise, by visualizing it in the manner described in the Quran and Hadeeths (narrations) with what Allah The Almighty has in it for the pious who feared Him.
Remind yourself of the Hell Fire and what Allah The Almighty has prepared in it for those who disobey Him.
Keep yourself busy with what benefits you and avoiding sitting idle, because if you do not keep yourself busy with what is virtuous and beneficial, it will lead you to become busy doing what is evil; plus sitting idle leads to seeking any company for the sake of companionship and to avoid loneliness, even if it is evil company that brings no benefit.
Go against your desires, because desires are the most dangerous thing, and that is why Allah The Almighty Says (what means): {Have you (O Muhammad) seen him who has taken as his Ilaah (god) his own vain desire?} [Quran 25:43]