How should I strategize/make plan on buying new things and preloved stuffs? I'm sure both kinds will give me different value. What is actually worth to be bought new -not only because of safety and hygiene factor- and what's not?

I would not mind getting bigger items brand new -- things like cribs, changing tables and toilet training stuff. These, I believe can be reused when the next babies come along and are long term investments. Clothes and toys can be preloved (washed and sterilised, of course).