Yes, as you get more money you can upgrade whatever you want.
Whether it be more storage, RAM, GPU, CPU, Mobo.

More RAM would help if you have alot of programs open at once.
CPU and GPU upgrades will give better performance in games, rendering, and better performance in general. Bigger hard-drive space would be good if you have alot of files such as games,movies,projects.
adding an SSD would decrease boot times and make opening programs snappy, as well as shortening load times on games.

what exactly is needed to add an SSD ?

Wubs wrote Yes, as you get more money you can upgrade whatever you want.
Whether it be more storage, RAM, GPU, CPU, Mobo.

More RAM would help if you have alot of programs open at once.
CPU and GPU upgrades will give better performance in games, rendering, and better performance in general. Bigger hard-drive space would be good if you have alot of files such as games,movies,projects.
adding an SSD would decrease boot times and make opening programs snappy, as well as shortening load times on games.

As Wubs says. I'd upgrade the total of 8GB of RAM to 16GB (2 x 8GB) or even 32GB (2 x 16GB) if you have enough money. More RAM means faster system performance. You could then upgrade your CPU and GPU as more modern hardware comes out that suites you best for what you use your system for.

yokedskydiver wrote what exactly is needed to add an SSD ?

An SSD. That's it. It's a storage drive, you just buy an SSD and plug it in to your system and it's good to. You'll want to re-install your OS on to it though.

I wouldn't recommend buying any more RAM. 8GB is fine, and it's about time you should look at a CPU upgrade IMO. You should start looking in to something like Zen or one of Intel's upcoming releases for a CPU/Mobo/RAM upgrade all at the same time. You'll need new DDR4 RAM when you upgrade CPU anyway, so I wouldn't advise investing more money in to DDR3 at this point. Your 8350 will still be fine for a while though.

A GPU upgrade wouldn't go amiss, 270x is pretty old and fairly low end. It's still a fine GPU though, and if it';s enough for you, there's not much point in upgrading it. However, a GTX 1060 or RX 480 or something like that would be a nice upgrade.

Definitely add an SSD. I'd upgrade that PSU as well, but I'd probably upgrade CPU and/or GPU before the PSU.

Also, depending on peripherals, an upgrade there could be a nice choice. Everyone should get a nice mech keyboard at some point.