Hope you've been working on getting that SR up as high as it can go, as the Overwatch team has announced the official end date for the third competitive season: February 21st.
Season 4 will begin just one week later, on February 28th.
Here's Blizzard on the rewards, which include a player icon, competitive points used to purchase golden weapons, and a spray:
If you completed your placement matches during Season 3, you will eligible to receive a special spray and player icon. These will be unlocked automatically when you log into your account the first time after the season ends. If at any point during the season you managed to break into the Top 500 players on your platform (and in your region), you’ll receive an extra player icon and animated spray on top of the other seasonal rewards.
Aside from sprays and icons, you’ll also receive a number of Competitive Points based on the maximum skill rating you achieved during the season.
Here’s the Skill Rating (SR) to Competitive Point (CP) breakdown for Season 3:
There are some things you should be doing before the competitive season ends, to make sure you can climb as high as you can go - namely, stop queueing up with your friends, and try to group with as few people as possible so you won't run into premade groups. If you try and become a leader for the groups you end up gaming with, your success and coordination in Overwatch should be much better.
Dustin Steiner has seen esports from nearly every angle, from tournament administration to live event coverage. He has worked in the space for over six years for outlets such as the Capcom Pro Tour, eSportsMax, ESFI World, Evil Geniuses and GameZone.