Cultivate Generous Thought and practice giving gifts to the Sanghas.

The Buddha once explained that it is a meritorious act even to throw away the water after washing one's plate with the generous thought: 

"May the particles of food in the washing water be food to the creatures on the ground." 

Even when the waste is discarded with pure thought as it benefits some one, it is also an act of indirect giving and do accumulate merit.
For example, when you throw empty mineral water bottles in dustbin think as above, it bring good virtue as it benefits some waste collectors. 

When, these waste brings so such merits, just think how much merits you will accumulate when you practice giving real gifts.

Giving is one of the essential preliminary steps of Buddhist practice. When practiced in itself, it is a basis of merit or wholesome karma. When coupled with morality, concentration and insight, it leads ultimately to liberation from samsara, the cycle of repeated existence.

So in the practice of giving keep one's mind pure, select the worthiest recipients available ( usually monks) , and choose the most appropriate and generous gifts one can afford.