Steemstats.com has just released a new feature to check the seriousness of the witnesses you vote for. Basically, after you connect to your steem account name on steemstats.com, you can see for each witnesses their numbers of mining misses and which versions of Steem they are running.
1) Vote for witnesses who are running the lastest update of Steem. It means they are reactive and running the right version of steem.
2) Vote for witnesses who don't miss their mining window. It means they are taking their business seriously and are stable.
To vote for witnesses, on the rightmost menu, there's a witnesses button. Click on it to vote for witnesses. You have 20 votes. The witness position is very lucrative (4800$ per day from mining) and should be kept for serious people working for the community. As far as I know, there's no rewards for voting witnesses except that the blockchain is working fine.
**We should all thanks 
jesta Steemstats post: https://steemit.com/steemstats/@jesta/steemstats-com-0-2-0-bringing-even-more-ways-to-track-account-activity-and-explore-the-blockchain
cryptoctopus Importance of your witness vote:
https://steemit.com/witness/@cryptoctopus/witnesses-exposed-what-witnesses-has-done-for-us-this-week-first-edition
jesta introduceyourself post: https://steemit.com/introduceyourself/@jesta/hey-everyone-i-m-aaron-aka-jesta-i-m-a-developer-sysadmin-gamer-and-lover-of-new-technologies-let-me-tell-you-how-i-ended-up
