Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
We ask Allah, the exalted, to grant all of us guidance and steadfastness on the straight path.
As for means that strengthen our faith, here is some advice:
1- Adopt good friends, and avoid bad ones, since good company leads to good deeds and consequences, and vice versa. So, you have to advise those who neglect their duties and ask Allah to guide them.
2- Do more optional forms of worship, such as prayer, fasting, reciting Qur'an and Zikr as well as avoid bad deeds, minor and major acts.
3- Repent from all misdeeds since the gate of repentance is open and Allah is Merciful and Pardoner.
4- Observe the Divine Orders and teaching in public and in secret.
5- Remember death and the Hereafter and the Reckoning Day when one will be personally before Allah.
6- Resort to Allah, the exalted, and praying to Him to grant you guidance, steadfastness and goodness Here and Hereafter.
Allah knows best.