Some of The Means By Way of Which Reward for Good Deeds Are Increased- By Imaam Sadi (rahimahullaah)
In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Question: What are the means and actions by way of which reward (for deeds) are increased?
Answer: As for the increase of reward for a good deed to ten times the like thereof, this has takes place in every righteous action, as Allaah (The Most High) said: [مَن جَآءَ بِٱلۡحَسَنَةِ فَلَهُ ۥ عَشۡرُ أَمۡثَالِهَاۖ – Whoever brings a good deed (Islamic Monotheism and deeds of obedience to Allah and His Messenger) shall have ten times the like thereof to his credit.” 
As for an increase beyond this – which is what the questioner intends (in his question)- it has its means; it is either related to the performer of the deed or the deed itself, and can be either related to the time and the place (i.e. a particular time and place mentioned in the authentic texts that the reward for good deeds are increased in that time period or place).
And among the most important means of increasing (the reward for good deeds) is when a slave fulfils sincerity to Allaah and adherence to the way of the Messenger (sallal-laahu-alayhi-wasallam) in his deeds. Therefore, (this increase occurs) when a deed is from those deeds legislated (i.e. in the sharia and not innovated) and the slave intends by way of it the Pleasure of Allaah and seeking Allaah’s Reward. (It occurs) when this intention is firmly established as the drive and goal behind the deed- such that the deed is (carried out) due to his belief in Allaah, belief in the Messenger, (obedience) to the command of Allaah, seeking the Face of Allaah and His Pleasure, just as it has been mentioned in a number of Aayaat and Ahaadeeth. Allaah (The Most High): [إِنَّمَا يَتَقَبَّلُ ٱللَّهُ مِنَ ٱلۡمُتَّقِينَ – Verily, Allah accepts only from those who are Al-Muttaqun]  That is: Those who fear Allaah in their deeds by fulfilling Ikhlaas (sincerity to Allaah) and Mutaaba’ah (adherence to the path of the Messenger). And likewise, the Messenger (sallal-laahu-alayhi-wasallam) said, ‘’Whoever fasts the month of Ramadhaan, his previous (minor) sins will be forgiven”; ‘’And whoever stands (in the night prayer) during Ramadan out of Imaan and seeking reward (from Allaah), then all of his previous (minor) sins will be forgiven”  and other texts besides these.
And because of this, the apparent actions have more virtue over one another in the presence of Allaah due to the Imaan and sincerity established in the hearts. Also abandoning the forbidden desires desired by the soul is included in those righteous actions that have virtue over one another due to the different levels of sincerity – when a (person) sincerely abandons them from the bottom of his heart and not out of other than sincerity. The story of the companions of the cave (i.e. in soorah Kahf) is a witness to this. 
Therefore, the means to increasing the (reward for good deeds) is that basis and foundation we have already mentioned – sound Aqeedah, a strong belief in Allaah and in His Attributes, a strong desire (to worship Allaah) and a fervent desire for goodness. For indeed those who are Ahlus Sunnah Wal Jamaa’ah in truth and those people of knowledge (i.e. the Rabbaani scholars)- those who possess knowledge of the perfect and detailed (explanation) of the Names and Attributes of Allaah and have a strong desire for the meeting with Allaah (in the Afterlife) – the reward for their deeds are greatly increased in a manner in which others who share the same belief can neither reach nor approach in the least. And this is why the Salaf used to say, ‘’When Ahlus Sunnah are held back by their deeds (i.e. not having numerous deeds), they are supported by their sound creed (i.e. the reward for their good deeds are increased due to been accompanied by strong Imaan, sound Aqeedah and adherence to the authentic Sunnah). 
 Minor sins forgiven when one fasts the month of Ramadhaan, see article on this link:http://salafitalk.net/st/viewmessages.cfm?Forum=11&Topic=6255
 Al-Fataawaa As-Sadiyyah. Page: 43. Abridged & Slightly paraphrased]
 Al-Fatawaa As-Sadiyyah page 44 & Sharh Al-Asbaab Wal-A’maal Allatee Yudaa-afu Bihaa Ath-Thawaab page 59-65. Slightly paraphrased & Abridged]