> Provide [...] contraceptives to those with high reproduction rates
This we should not do. First, Malthusians have always been wrong and I claim will continue to be wrong. Second, contraception encourages declining birth rates and low birth rates are destructive to societies. Third, contraception is intrinsically immoral because it frustrates and perverts the function of the sexual faculties (it's the analogue of bulimia). Fourth, contraception has the psychological effect of divorcing the intrinsic function of sexual intercourse from pleasure which results in a hedonistic view of sex, the objectification of people, and exploitative attitudes, among others. Not exactly a winning recipe for a healthy society. I would also emphasize the distinction between promotion and permissiveness; I am arguing against promotion only and a culture that normalizes its use as opposed to one that merely tolerates it.
> (see China vs India)
China is below replacement (1.70). India is at replacement (2.18). Fertility rates are low everywhere except Africa. I think Africa has had enough of philanthropic "interventions".
> Practice secular (or religious) asceticism and be comfortable with that.
You don't need to be ascetic. You just need to avoid prodigality and the consumerist vice of excessive acquisitiveness. Where clothing is concerned, prefer high quality, classic styles that last, even when they cost more upfront. Don't live beyond your means. Don't buy stuff you don't need or doesn't contribute real value to your life. Don't buy impulsively (unless you want to fill your garage with garbage). All these are just common sense.