I have been tracking my Splinterlands earnings this year (January +136.44$ | February +105.25$) and will continue to make posts on how new players can best grow their own card collection increasing their overall earnings with the game.
WEEKLY SHARE YOUR BATTLE CHALLENGE
Splinterlands has an active community on the Steem blockchain where many players get rewarded for making blog posts about the game. The Splinterlands team has a lot of SP in order to provide for resource credits and is able to give out good-sized upvotes. They currently have a weekly Share Your Battle Challenge where one specific card is highlighted. Everyone that makes a post sharing their battle with that specific card will be able to get a good upvote for it (if it's done properly)
For all details, you can check out their post on it here
The post-earnings are paid out 7 days after the post was made. Half of them will be in SP which can be used as Resource Credits to be able to make more transactions daily on the Steem blockchain. The other half of the earnings are liquid and can be used to buy more cards which will help you get higher on the rankings or to cash out to recover the 10$ cost of the Summoners Spellbook which is needed in order to be able to get rewards from the game.
How To make posts on Steem
Creating a Splinterlands account is really easy and can be done within a minute. (Anyone who signs up with my Affiliate Link and gets the summoners spellbook will get a whole bunch of extra cards leased out to them which gives a real early game advantage and can get up to Rank 1600. Check here for details).
If you make a free instant account on the splinterlands site which can be used to test out the game, you won't instantly get your private keys to login to the steem blockchain. They are part of the package when getting the 10$ Summoners Spellbook along with being able to get daily quests, earn reward chests, end of season rewards, DEC earnings, join tournaments,... Once you get the summoner's spellbook you should be able to find the private keys on the splinterlands website.
Once you have your private keys you can use them to log in to any interface that connects to the steem blockchain using the keychain extension (Link) in a safe way. Some of the different blogging interfaces are https://steempeak.com/ | https://busy.org/ | https://steemit.com/.
Once you are logged into your Steem Blog, you can click the pencil button (in steempeak) and click create a post to start writing. I would suggest taking a look at some of the other 'share your battle' posts that got upvoted as a reference on the layout.
You can also join the Splinterlands community (Link) to easily find posts from other players and make some friends in the process. There are also many card giveaways by players you are able to take part in to further grow your collection.
Good luck and if you have any questions regarding the game or Steem in general, feel free to ask away!