Salam,
What is taqwa? Taqwa is avoiding all the sins ( big or small ) with the fear of Allah in ones heart. Fear of Allah means that when one commit some sin wither big or small, he finds a sudden thought that Allah is watching him and he will be questioned about this deed on the day of judgment.
It is very important for all the muslims to have taqwa in their hearts. If someone commits a sin, then he should try to give it a thought that on the day of judgment that Allah will question him for this deed, or Allah is watching him doing that deed if he thinks that he alone and no one will see him. Allah says in the quran ( 1:2 )
ذَٲلِكَ ٱلۡڪِتَـٰبُ لَا رَيۡبَۛ فِيهِۛ هُدً۬ى لِّلۡمُتَّقِينَ
" This is the Book (the Qur'ân), whereof there is no doubt, a guidance to those who are Al-Muttaqûn [the pious and righteous persons who fear Allâh much (abstain from all kinds of sins and evil deeds which He has forbidden) and love Allâh much (perform all kinds of good deeds which He has ordained)]. "
The mafhoom of this ayat is that quran is for those people who have taqwa in their hearts. It is a guidance for only those who have taqwa. If one have taqwa, then he/she will perform almost no sins, because the thought that he/she will have in his mind all the time will be that whatever i will do, Allah is watching, whatever i say, Allah is hearing, and whatever intention i have, Allah knows all. In this manner he will try to perform more good deeds and will be vary of his bad deeds. If one has taqwa he/she will feel ashamed of all the bad deeds that he/she did in the past or is still doing. When he/she will be vary of the bad deeds that he/she did, then he will surrender himself to Allah and will ask for forgiveness i.e taubah ( the true taubah ).
When having taqwa he/she will try to behave as much good as possible because he/she will have this thought that Allah is watching him all the time, whenever he/she is in a crowd, alone or anywhere in the world.
سُبۡحَـٰنَ رَبِّكَ رَبِّ ٱلۡعِزَّةِ عَمَّا يَصِفُونَ (١٨٠) وَسَلَـٰمٌ عَلَى ٱلۡمُرۡسَلِينَ (١٨١) وَٱلۡحَمۡدُ لِلَّهِ رَبِّ ٱلۡعَـٰلَمِينَ (١٨٢)
