Installing Ubuntu for Part 2 on an XPS 15 9550 notebook

Is the dual booting procedure remains same if we begin from a dos based laptop ->install win 10 -> install Ubuntu?

I have a 1 TB HDD.

My doubt is that should I leave the free space(512 GB)while installing windows as unallocated space so that I can install Ubuntu there?

Can someone shed some light in the partitioning part of win and Ubuntu both?

Thanks in Advance…