The main objective of unattained ordinary Dharma practitioners in our lives are to to accumulate merits and wisdom. Merits are generated only through the kindness of the Guru by doing any work of the Guru. Otherwise any act of goodness can only be deemed to have generated good karma. Hence, one should seek out a Guru suitable to one's aptitude and hopefully the Guru also agrees to having one as a disciple. Then one should take refuge in the Guru to seal the Guru-disciple relationship. Then by the power of good Samaya to the Guru, any act in accordance with the Guru's wishes and aspirations can be consider to have generated merits. Of course it also depends on the motivation of the disciple in doing this work.
As such, if one has the money (any amount), one should donate to the Dharma Center rather then any other charities. Via the Dharma center, the money can then be channeled to support the Center, the Sangha, the Dharma work which may include orphanages, retirement homes or any needy causes. This is the wiser way to gain merits. Beyond money, one should work for the Dharma via the center as a way of serving the Guru. There can of course be other ways to serve the Guru as per the Guru's instructions.
Through serving the Guru, the Center and practicing the Dharma in our daily endeavors especially practicing the 8 verses of mind transformation and most importantly through studying the Lamrim/sutras and practicing the teachings, contemplation and prayers one accumulates wisdom.
As merits and wisdom goes hand in hand, by accumulating one we indirectly gain the other, we need to be wise that we need to strike a balance with both. That is to say, we should not be over zealous in focusing on merits and forget about wisdom. Hence, if we know that the orphanage needs the money more than the Dharma center, of course then we should apply wisdom and donate to the orphanage.
So, it all depends on the situation.