We all know that the devil is the most evil creation of Allah. He is sent to guide everyone towards the right path which leads to hell as it is mentioned in the quraan.
لَأَمْلَأَنَّ جَهَنَّمَ مِنَ الْجِنَّةِ وَالنَّاسِ أَجْمَعِينَ
"I will fill Hell with jinn and mankind together" says Satan.
So now that we know what his objective is, what we need to do is to understand his strategies. The first rule in warfare is "know your enemy". For us to fight him well we need to know what weapons is he using and where will he be aiming at! Oh he knows us pretty well and he is using this at its best. We need to understand how he works in order to avoid falling into his traps.
Satan is a genius and his strategies are very effective. He leverages on our weakest points and leads us to self destruction. In addition to that, he will not be held liable for them on judgment day. Only we will be responsible for our actions as the ayah says:
وَقَالَ الشَّيْطَانُ لَمَّا قُضِيَ الأَمْرُ إِنَّ اللّهَ وَعَدَكُمْ وَعْدَ الْحَقِّ وَوَعَدتُّكُمْ فَأَخْلَفْتُكُمْ وَمَا كَانَ لِيَ عَلَيْكُم مِّن سُلْطَانٍ إِلاَّ أَن دَعَوْتُكُمْ فَاسْتَجَبْتُمْ لِي فَلاَ تَلُومُونِي وَلُومُواْ أَنفُسَكُم مَّا أَنَاْ بِمُصْرِخِكُمْ وَمَا أَنتُمْ بِمُصْرِخِيَّ إِنِّي كَفَرْتُ بِمَا أَشْرَكْتُمُونِ مِن قَبْلُ إِنَّ الظَّالِمِينَ لَهُمْ عَذَابٌ أَلِيمٌ
"And Satan saith, when the matter hath been decided: Lo! Allah promised you a promise of truth; and I promised you, then failed you. And I had no power over you save that I called unto you and ye obeyed me. So blame me not, but blame yourselves. I cannot help you, nor can ye help me, Lo! I disbelieved in that which ye before ascribed to me. Lo! for wrong-doers is a painful doom".
It is important to know that this is a psychological warfare we fighting, he will whisper to us and we will hear it as what it seems like "thoughts" in our head as if we are talking to ourselves. Therefore, what he is doing is only convincing us to do what he wants us to do, the final decision is still ours!
Some of our weakest points are mentioned in the bible as the seven deadly sins.
Greed, anger, sloth, envy, gluttony, pride and lust! These are satan's weapons which he uses brilliantly against us. Since every action has a reaction, it comes down to our reaction or what I would call "defense weapon" against him on these battle grounds:
These are some of the common thoughts we tend to think sometimes
Greed: Everything is ever enough, there's always more.
Envy: Always look at what other people's pockets, success, assets... etc.
Pride: The attention, the VIP status, the power, you are above the rest!
Defense: By saying الحمد لله .
Gluttony: Eat your guts out, you'll regret not eating this later, you still can stuff them down, you're still healthy, don't stop.
Defense: Start by saying بسم الله الرحمن الرحيم and end by saying الحمد لله .
Anger: How could they do that to you? You cant let it go! Make them feel what you felt! Let everyone know what happen! I feel like killing them!
Defense: By saying لا حول و لا قوة الا بالله .
Lust: OMG he/she is so hot! Try to get him/her to sleep with you tonight. Its worth it! If only he/she is in front of me now... I'd (fill up the rest)
Defense: By saying استغفر الله
Sloth: Its okay to miss fajr once in a while! go back to sleep! You can't go back to sleep after wudhu.. By the time you finish your wudhu, fajr time is already gone! or my favorite.... There's still time!
Defense: By saying اعوذ بالله من الشيطان الرجيم
Another way to defend ourselves is to build a shield/strong fortress against him by reading Ayat alkursi, Surah Alfalaq and surah Annas. This will keep him away from us as we will be under the protection of an army of angels sent by the almighty.
As you can see that is very very simple to defeat him, the weapons which we use are words from the almighty himself! In addition to that, satan himself is weak as it is mentioned in the quraan
إِنَّ كَيْدَ الشَّيْطَانِ كَانَ ضَعِيفاً
"The devil was weak"
So don't fear him, fight him well and heaven itself will be your reward!