ok then to get a better idea what you have I need the following details (you can use speccy to get them if you like)
CPU we have at FX6300
Motherboard you have Gigabyte 78LMT-USB3 rev 6
RAM make/model/size?
Hard drive make/model/Size?
video card make/model?
Power Supply make/model?
why all this, to find out if a simple cpu upgrade will bring th maximum of improvement over value.
i.e. an SSD would improve speed over a HDD, as will more ram if you only have 8GB.
But as for cpu you are looking at FX-8300, 8310, 8320, 8350, or 8370
as for a cooler for it, you would need a good one to make sure to keep it running... so for 8xxx series I would suggest a CRYORIG - H7
https://pcpartpicker.com/product/93Crxr/cryorig-cpu-cooler-h7 if not available then a Cooler Master - Hyper 212 EVO would do, if you dont overclock the cpu.
as for SSD, you could depending what size your drive currently is, clone your hdd to the ssd, and then continue to use the HDD for data/backups
as for ram, if you only have 4 or 8 I might suggest 16GB but this all depends what your going to use your pc for (work or gaming)
and finally depending on your cpu/video card, those may need upgrading...