Al-jawab billahi at-taufeeq (the answer with Allah's guidance)
Ways to increase our Imaan:
1) Love Allah Ta'ala and His Prophet (Sallallahu Alaihi Wasallam) and follow his Sunnah.
2) Have Tawakkul (trust) in Allah Ta'ala.
3) Always have Sabr (patient).
4) Safeguard your tongue, eyes, stomach etc, from Haraam actions.
5) Stay away from Sins.
6) Increase good deeds i.e. offering optional prayers, fasts, charity etc.
7) Seek Knowledge. People who have Taqwa are those who have knowledge.
8) Always remember Allah Ta'ala.
9) Always remember death, as death is the destroyer of all pleasures. Remember what comes after death i.e. grave, when we are judged, whether we will be in paradise or hell.
10) Make Du'a to Allah Ta'ala. Du'a is a weapon of a believer. We need Allah Ta'ala.
Please read these Ahadith and act upon it: http://www.witness-pioneer.org/vil/hadeeth/riyad/default.htm
May Allah Ta'ala make you from the pious. Ameen.
Some Du'as for Hidaayah and to strenghen Imaan:
"Allahumma Inni As'aluka Imaanan La Yartaddu Wa Na'eeman La Yanfadu Wa Muraafaqata Nabyinaa Sallallahu Alaihi Wasallam Fee A'laa Darajatil-Jannah Jannatil-Khuld."
Translation: O Allah, I ask you for such Imaan that does not waver and tranquility that does not diminish and the companionship of our Prophet (peace and blessings be upon him) in high stations of everlasting Jannah."
"Allahumma Inni As'aluka Sihhatan Fee Imaanin, Wa Imaanan Fee Husni Khuluqin, Wa Najaahan Tutbi'uhu Falaahan, Wa Rahmatam Minka, Wa 'Aafiyataw Wa Maghfiratam Minka Wa Ridhwaanaa."
Translation: O Allah, I beg of you that I may be awarded perfection of faith, a belief which is accompanied by virtuous manners, prosperous life (in this world) which is followed by complete success (in the life of the Hereafter), mercy, peace and forgiveness from You and Your pleasure.
"Allahumma-hdini Wa Saddidni."
Translation: O Allah, guide me aright and keep me steadfastness.
"Allahumma Inni As'alukal Hidaayata Was-Sidaada."
Translation: O Allah, I beg of your guidance and steadfastness.
"Allahumma Inni As'alukal Huda Wat-Tuqa Wal 'Afaafa Wal Gina."
Translation: O Allah, I beg of you guidance, piety, chastity and independence (from your creation)
(Al Hisnul Hasin Pg.282 and 288)
And Only Allah Ta'ala Knows Best.