Allah 
has given a special status to certain days, months, places, and people. The Prophets of God are the most honored among mankind; Makkah is the holiest of all cities; Ramadan is the best month; and the Night of Power (Laylatul Qadr) is the greatest night of the year.
Allah says in the Qur'an:
إِنَّ عِدَّةَ الشُّهُورِ عِندَ اللّهِ اثْنَا عَشَرَ شَهْرًا فِي كِتَابِ اللّهِ يَوْمَ خَلَقَ السَّمَاوَات وَالأَرْضَ مِنْهَا أَرْبَعَةٌ حُرُمٌ ذَلِكَ الدِّينُ الْقَيِّمُ فَلاَ تَظْلِمُواْ فِيهِنَّ أَنفُسَكُمْ وَقَاتِلُواْ الْمُشْرِكِينَ كَآفَّةً كَمَا يُقَاتِلُونَكُمْ كَآفَّةً وَاعْلَمُواْ أَنَّ اللّهَ مَعَ الْمُتَّقِينَ 9:36)
"Indeed, the number of months with Allah is twelve [lunar] months in the register of Allah [from] the day He created the heavens and the earth; of these, four are sacred [...]" (Qur'an, 9:36)
These four sacred months were mentioned by the Prophet 
during his farewell pilgrimage:
"O People! Time has gone back to how it was at the time Allah created the Heavens and the Earth. A year has twelve months, four of which are sacred, three consecutive, Dhul-Qi'dah, Dhul-Hijjah, Muharram, and Rajab." (Bukhari)
As we look through the Qur'an and Sunnah (Prophetic tradition), we are taught to respect and honor what God and His Prophet have honored. These sacred months are a time for us to reflect on our lives, exert ourselves in extra worship and ask Allah for His forgiveness.
Specifically, Allah reminds us to guard our actions during the sacred months:
يَا أَيُّهَا الَّذِينَ آمَنُواْ لاَ تُحِلُّواْ شَعَآئِرَ اللّهِ وَلاَ الشَّهْرَ الْحَرَامَ وَلاَ الْهَدْيَ وَلاَ الْقَلآئِدَ وَلا آمِّينَ الْبَيْتَ الْحَرَامَ يَبْتَغُونَ فَضْلاً مِّن رَّبِّهِمْ وَرِضْوَانًا وَإِذَا حَلَلْتُمْ فَاصْطَادُواْ وَلاَ يَجْرِمَنَّكُمْ شَنَآنُ قَوْمٍ أَن صَدُّوكُمْ عَنِ الْمَسْجِدِ الْحَرَامِ أَن تَعْتَدُواْ وَتَعَاوَنُواْ عَلَى الْبرِّ وَالتَّقْوَى وَلاَ تَعَاوَنُواْ عَلَى الإِثْمِ وَالْعُدْوَانِ وَاتَّقُواْ اللّهَ إِنَّ اللّهَ شَدِيدُ الْعِقَابِ 5:2
"O you who have believed, do not violate the rites of Allah or [the sanctity of] the sacred month [...]" (Qur'an, 5:2)
He reminds us not once but twice to be careful of what we do during a sacred month:
"[...] so do not wrong yourselves during them (i.e., the sacred months) [...]" (Qur'an, 9:36)
These two verses show us the importance of being a conscientious believer. The only way we can make sure we do not wrong ourselves during the sacred months is to be conscious of our actions. Time and time again we forget or are lax in our duties to God. Allah has given us these sacred months to turn back to Him and to take account of ourselves.
The month of Rajab comes at an important time of the year for us. The coming of this month means that we are close to yet another Ramadan, God Willing. While the validity of certain narrations or specific acts of worship for this month are disputed, we as average Muslims can use this month with the intention to mentally and physically prepare for Ramadan.
How can we honor the month of Rajab and use it as a preparation for Ramadan?
Reflect on your Life and Deeds
Take some alone time and ask yourself the hard questions we normally don't like to think about: If I died today, where would I stand with Allah? Have I prepared for Ramadan? Have I been conscious of what I am saying and doing to those around me? Am I stagnant in my worship?
Deprive your Nafs (lower self)
I was with my brother one day and I mentioned that I was hungry and wanted to get something to eat. He told me: "Teach your nafs a lesson. We shouldn't always give it what it wants." This does not mean that we starve ourselves or do not take care of our bodies. One of the goals of Ramadan is to increase in our God-consciousness by not indulging ourselves with what our soul desires. Eat a simple meal for a few days instead of an expensive or huge meal. Wake up early and go for a walk. Pray extra prayers. Go to the mosque for fajr if you normally do not do so. Exert yourself and do something to "teach your nafs a lesson."
Fasting
There is no better way to prepare for Ramadan than to fast some extra days. A'isha 
was known to fast during the summer, and when the scholars would mention her habit, they would add: "If the price is cheap, then everyone will buy it." Ibn Rajab explained: "She wanted to do those actions that only a few were capable of due to how hard it was to do them, and this is indicative of the high aspirations she had." While we can't get out of having Ramadan in the summer, we can follow our mother A'isha and be of the few that do something valuable before we are all obligated to fast. Now is the time to not only prepare for fasting but to gain some reward as the temperature rises.
Remember the Hereafter
The Prophet said:
"Hell complained to its Lord saying: O Lord! My parts are eating (destroying) one another. So Allah allowed it to take two breaths, one in the winter and the other in the summer. The breath in the summer is at the time when you feel the severest heat and the breath in the winter is at the time when you feel the severest cold." (Bukhari)
Charity
Most of us do some act of charity every day without realizing it. In this sacred month, be charitable with the intention of pleasing God. Being courteous, helping someone, feeding another, saying a good word, sharing a reminder and even abstaining from doing a bad deed are all non-monetary forms of charity taught to us by the Messenger.
Supplicate (make du`a') to Allah
Ask for His forgiveness and guidance. Ask Allah to bless us to reach Ramadan and to make the month of Rajab, and the following month of Sha'ban, a means for us to prepare for Ramadan. It is reported that the Prophet of God used to supplicate when Rajab came, "O Allah! Bless us during Rajab and Sha'ban, and let us reach Ramadan."
Take Care of Your Tree
Ibn Rajab used to say:
"The year is like a tree. The days of Rajab are its foliation. The days of Sha'ban are its branching and the days of Ramadan are wherein its fruits are reaped. The reapers are the believers. It is befitting for the one who has blackened his pages with sins to whiten them with repentance in this month, and for the one who has squandered his life in idleness to profit in it from what remains of his life."
Source - SuhaibWebb - Amatullah