Need some recommendations on parts to upgrade my PC...Any assistance is appreciated.

Beni

So my budget is tight and I wanted to find out what upgrades were compatible with my current build & spec's listed below. Not sure what's interchangeable without changing my MBD.  I'm wanting to play the latest games such as COD: MW, Apex Legends and Horizon Zero Dawn to name a few. I also want to be able to use this PC as a workspace for rendering & utilizing Adobe Creative Suite as I'm trying to make content in 1080p.

Realistically I have maybe $300 to spend on a part. I've been trying to research the best part to change and it seems like my best bet is the GPU. Any suggestions on what I could upgrade that part to?

CPU: Intel Core i5-8600K

GPU: Nvidia GTX 1050-Ti
SSD:  SSD 120GB
HDD: WD Black 1TB
RAM: G.SKILL Aegis DDR4 2400 C17 2x8GB
MBD: Asus PRIME Z370-A

TSTonyV

You're right, the best bet is going to be your GPU. The 8600k is still a solid gaming processor and you'll get the most benefit out of a GPU upgrade. 

AT $300 the GPUs I would look at would be the RTX 2060 and RX 5600XT.