Investing in Dharma?
If you can spare some money, by all mean please continue to donate to charity. Imagine you were a starving child in some war-torn country, getting a hot meal won't help you attaining enlightenment but it does help relieving a horrible kind of suffering: starvation!
Then one can always start with him/herself. Observing the Five Precepts whole-heartedly itself would generate tremendous amount of merits according to AN 8.39:

...&quot;Now, there are these five gifts, five great gifts — original, long-standing, traditional, ancient, unadulterated, unadulterated from the beginning — that are not open to suspicion, will never be open to suspicion, and are unfaulted by knowledgeable contemplatives &amp; brahmans. Which five?
&quot;There is the case where a disciple of the noble ones, abandoning the taking of life, abstains from taking life. In doing so, he gives freedom from danger, freedom from animosity, freedom from oppression to limitless numbers of beings. In giving freedom from danger, freedom from animosity, freedom from oppression to limitless numbers of beings, he gains a share in limitless freedom from danger, freedom from animosity, and freedom from oppression. This is the first gift, the first great gift — original, long-standing, traditional, ancient, unadulterated, unadulterated from the beginning — that is not open to suspicion, will never be open to suspicion, and is unfaulted by knowledgeable contemplatives &amp; brahmans. And this is the fourth reward of merit...

Finally, one can share the Dhamma to others if the conditions are appropriate according to MN 58:

...In the case of words that the Tathagata knows to be factual, true, beneficial, but unendearing &amp; disagreeable to others, he has a sense of the proper time for saying them...