Q: Should I make a partition for Ubuntu before installing? Should I make a separate partition for Ubuntu before installing ? I'm just wondering if it would be beneficial.
[Dual boot with Windows 8.1]

A: NOT FROM WINDOWS!!!
The Windows disk partitioning tool has the unfortunate habit of converting from a standard Master Boot Record (MBR) format to Microsoft's proprietary Logical Disk Manager (LDM) configuration, which Ubuntu's installer doesn't support. Thus, if you try to create a partition for Ubuntu in Windows, you run the risk of creating extra work for yourself, since you'll need to use third-party tools to convert back from LDM to a standard MBR-only configuration.
In fact, I'd go so far as to say that the Windows partitioning tool is one of the buggiest partitioning tools in common use today. I've seen it do other strange things, like embed a primary partition inside an extended partition (a definite no-no).
That said, I've heard of fewer problems with the Windows partitioner on GPT disks, which are used by the vast majority of computers that ship with Windows 8 and 8.1. Still, I recommend using the Windows partitioner as little as possible.
The one thing for which the Windows partitioner is likely superior to the Ubuntu installer's partitioner is in shrinking the existing Windows partition. Just shrink that partition, though; don't create new partitions! Leave that task to the Ubuntu installer. You can let it do so automatically if you want to use the defaults, or use the "Something Else" installation option to set up a separate /home partition or otherwise deviate from the defaults.

A: Yes, Ubuntu need at least a separate partition to work. If you want better stability, also make a Linux SWAP partition sized like the amount of your RAM, so Ubuntu will be able to use you disk like a RAM if necessary.
If you make a separate Home partition and a root partition for the system your personal data will be safer; this is a classic Linux partitioning process.
The default Ubuntu installation will install anything on one big partition: it's easy to manage but can be really "fragile" if something happens.
Always do a backup of your personal data before a partitioning process.
Do not try to install Ubuntu with Wubi & Windows 8/8.1 because that will not work for compatibility issues.
If in doubt, please follow the Official Ubuntu installation guide or ask by commenting under here. Click the UP arrow if I'm of any help.
Good day.
