Most of the time we are under control of our mind and old habits.If a beginner wants to break the old habits and get more control of it.From where do they should start ?
One starts by seeing with insight how the old habits are disadvantageous, unsatisfactory (incapable of bring lasting hapiness), dangerous, harmful &/or promote suffering.
One starts by seeing with insight the advantage & benefit of giving up those old habits.
The Dvedhāvitakka Sutta is one of many suttas describing how the Buddha, before his enlightenment, reflected upon the advantages & disadvantages of differing types of thinking.
The Upanisa Sutta states a cause of faith in Buddhist practises is the experience of suffering.
The short answer is BE WISE. BE PURE IN DEED, SPEECH AND THOUGHT.
The wise are controlled in deed, they are controlled in speech, they are controlled in thought. Only if you could stay heedful, would you be able to put out the fire of lust (Ragaggi), the fire of hatred (Dosaggi), and the fire of delusion (Mohaggi) that are waiting to flare up at any moment. We all have these traits to a lesser or greater degree. Otherwise we cannot be living in the society. Since one does not live alone, living in unity in society requires self-awareness, self-control, adaptability, non-violent attitude and good-will. Buddhists are taught to diffuse the Four Divine States of Mind: loving-kindness, compassion, sympathetic joy and equanimity towards all sentient beings who may be of different nationalities, religions and environments. The Five Precepts that we follow help us to abstain from killing, stealing, sexual misconduct, false speech, and intoxicants which cause carelessness. We should be kind, honest and mindful. Then our society will reach the goal that persons can live together peacefully and in mutual trust. In the scriptures it is said:
"Good is restraint in action,
And good restraint in speech,
Good is restraint in mind,
Restraint throughout is good.
Well guarded is he said to be
Who is ashamed of sin, in all things self-controlled "'
Stop trying to control is a good way to gain some control(: Insight meditation(I assume your talking about insight so if your practicing something else than this answer probably doesn't apply) is so easy in a way because the only thing you ultimatly have to do is experience what is going on in your own experience. Although it's good to do preliminary stuff like doing good sila so that the mind can better become clear and concentrated and making sure the facilities are ballanced. In insight meditation there are ways to control your own faculties but it's better to find a good teacher. They will know how to guide you so your practice is effective. -Good luck
You start with self restraint. Initially this would be having a list of rules or code of conduct you try to adhere to. When your old habitual or reflexive responses try to manifest himself try to take a step back, compose yourself, see if the actions are in the list of acts you want to avoid if so avoid it. Also have a list of action you want to do as try to do it when you get the opportunity. As you go on see if the actions are for the good of oneself or that of others, or one's action are the way you want to treat others, then follow through accordingly and if not abstain from such action. [Velu,dvāreyya Sutta, Sedaka Sutta] Finally as your wisdom increases see if the metal states and content (Refer to Comprehensive Manual of Abhidhamma by Bhikkhu Bodhi and Kīta,giri Sutta section on feelings) are favorable and then follow through if the actions are conducive.