What should I up next?

[Ashton_sama]

My RIG
UserBenchmarks: Game 63%, Desk 48%, Work 22%
CPU: Intel Core i5-3470 - 69.5%
GPU: Nvidia GTX 1060-6GB - 78.3%
HDD: Seagate ST31000322CS 1TB - 42.9%
RAM: Kingston 99U5474-038.A00LF 1x4GB - 28.3%
MBD: Asus P8H61-M PLUS V3
CASE: In Win ROG Edition
NO. OF FANS: Processor Stock Fans... That's all...

I am wondering what to upgrade next, should I go for a SSD first or get fans for cooling? Cuz I feel like changing straight to M.2 instead of using SATA now, but it can be use for future as well so I dont mind getting SATA now. Or any other suggestions for my rig other than SSD & Fans? 
I won't be changing my DDR3 RAM as I'm waiting for new 8th gen card and mbd which are DDR4 RAM

[PerfectPlasma]

M.2 isn't faster than SATA. NVME is. But hella expensive as well.

You'll be better off getting fans first and then SSDs. Try and fit in an aftermarket cooler like the MasterLiquid 120, which isn't much more expensive than the Hyper 212.

[Herman Mcpootis]

you'll be fine with just the stock cooler unless it's overheating so I'd recommend you get the ssd first. 

[PerfectPlasma]

Just now, herman mcpootis said:

you'll be fine with just the stock cooler unless it's overheating so I'd recommend you get the ssd first. 

I know stock is fine but lower temps is generally better for your components

[Ashton_sama]

16 minutes ago, PerfectPlasma said:

I know stock is fine but lower temps is generally better for your components

Cuz I plan to get a AIO water cooler for my processor next year, but right now just trying to gets some fans for better air flow, thought it's not over heating cuz of my air conditioner.

[Ashton_sama]

22 minutes ago, herman mcpootis said:

you'll be fine with just the stock cooler unless it's overheating so I'd recommend you get the ssd first. 

Samsung 850 evo? 256gb or 512gb? Or any other suggestions?

[PerfectPlasma]

Just now, Ashton_sama said:

Cuz I plan to get a AIO water cooler for my processor next year, but right now just trying to gets some fans for better air flow, thought it's not over heating cuz of my air conditioner.

Then you'll be fine. An SSD and more case fans will do you good.

[Ashton_sama]

Just now, PerfectPlasma said:

Then you'll be fine. An SSD and more case fans will do you good.

Which should I go first? ?

[PerfectPlasma]

1 minute ago, Ashton_sama said:

Samsung 850 evo? 256gb or 512gb? 

the 850 evo is fine. 512 is the most i'd go for because after that you're probably needing mass storage. Which is a HDD's job. Probably better with the 512 is you can fit it in.