/boot 300 MB
Swap 256 KB
/ 8000 MB
/home the rest
That is what I recommend when someone has plenty of ram. You shouldn't go less than 256kb on swap because mint does not like it. 8gb for mint instal is usually more than enough, mint only takes up about 3-4 so you have 4gb left however if you would like to then feel free to bump it up to 10gb or even 15gb. I just usually do 8gb and if I need more later I take it from the /home partition and add it to the / partition.
Case: Thermaltake V9 Blacx Motherboard: Asus P8Z77-LK Processor: I5 3570k OC 4.6ghz GPU: EVGA GTX 660 Cooler: Coolermaster TPC-812 Ram: Corsair 8gb DDR3-1600LP PSU: Corsair HX-850 HDD:Intel 520series 180gb SSD, 1TB WD Black, 2 Seagate 1tb drives Monitor: Asus 248QE 144hz