Your ping depends on the location of the server and your location. The further you live from the server location, the higher your ping is, yet you can make your ping more stable. NEVER use wireless connection, always use a wired connection (Ethernet cable). Some things you can do are restart your router/modem several times, maybe get a better router/modem and close any other apps that are using up bandwidth (e.g. YouTube). Check if someone else is using your connection ;). Plus, it may be peak hour for your area, and as a result, your connection may be slow. Also, your ISP could be throttling/restricting your connection because you've used up all your data, or haven't paid your Internet bills :P. Or they are doing maintenence.
The only way you can lower your ping is to move closer to the server location (e.g move to another country) or choose a closer server. I wouldn't recommend moving closer to the server location :P. Ping reducing software such as WTFast don't work, it just makes the ping worse.