Contact management, 2017
Many sites have different bonuses eg yahoo can import fb while fullcontact connects with twitter. I don't think its good to leave contacts on only one site , just incase one is down.  I also like having 'hard copy'. I do this every so often.


Mac Sierra
  EXPORT contacts->  all contacts -> edit -> select all (see count change) -> edit export-> vcard
 
  IMPORT to fullcontact (FC) site  ,
    settings -> import , selecting  the Mac-vcard from above
     link your social media contacts like twitter,  and  linkedin  if you wish
    EXPORT     fullcontact site:   backups-> select latest file
 
    IMPORT into yahoo, select contacts icon, select  import contact , add gmail and facebook if you wish
    EXPORT actions dropdown  select yahoo-csv , or mac vcf
   
    outlook IMPORT, select a file from above  and allow to select  a file  , then click upload , located  top left of popup box .  However  there is 2k number of contacts  limit and 5mb file size upload limit.
     EXPORT , outlook/hotmail : manage ->export
   
 IMPORT gmail , more-> import
 export gmail, select all the checkbox, more ->export , making sure to select ALL (third radio button)

 now import the gmail into Mac Sierra, file-> import

This process allowed me to save facebook, linkedin, google+ and twitter contacts and finally all in one file on my mac, where i can permanently store on backup drive

El Capitan Headaches and Possible workaround

Due to upgrade  of my Mac from  Lion to El Capitan,  I had lost functionality of several apps. These include the following:

•                     cisco any connect
•                     comodo anti virus
•                     find any file
•                     ccleaner

NEW annoying settings

• The auto hide of the  main toolbar on top. I'm using firefox and it constantly hiding the dock and toolbar (apple)  . It leaves a empty space on the border, so it's not full screen.
• Additionally,  I lost all the 'pinned' folders in Finder.
• The Activity monitor lost it's pie chart UGH!  now I have to terminal window  'top -c cpu' to get info.

PUSHED software

• El Capitan imposed the map, google map is best, esp on phone , El Capitan map is very slow not useful most use gps phones. 
• Also ,  Apple push the photo app.  I use Image Capture for reading digital photos off my cam.  I like Picassa for management instead and Gimp for editing.
• The ibook, hmmmm. It don't download any books, there is no history button and not convent to place on mobile device.  Google books and simple search of pdf are much easier.

UNBOOTABLE
Yes after El Capitan upgrade, it was working fine until I needed to reboot. Well that's when all hell broke loose.  I could not reboot.  Luckily  , I had phone to google for some answers. It took two days(my off time from full-time).

It's very important to learn shell/bash, scripting.  LEARN IT.
---- get to terminal--
So after following many forums and searching,  many stated they had issues  with Library Extensions.  I had a 'panic' message, but ONLY after I had to do a ctl-R , then go to terminal.  I then needed to set the boot to    sudo nvram boot-args=”-v”  as the SAFE MODE (shift -S) never worked for me .
This is when I was able to see 'panic' message. This listed some com. eltima sync.....

 -----get root----
But wait, you'll need to enable the root, because El Capitan  developer  thought it was a great idea to play nanny with machine that you paid for....
how to enable root:  http://www.macworld.com/article/2986118/security/how-to-modify-system-integrity-protection-in-el-capitan.html

---- fixing---
Diagnostic Reports (/Library/Logs/Diagnostic Reports) did not show anything in particular. I was able to attempt rebooting,  but only 'after reinstalling'  El Capitan, again worked until  time to reboot again. So my joy was quickly washed away LOL.

After googling eltima.... , using the find / -iname *eltima* , in terminal

Finally, the fix was  in volume/Machine HD/system / LibExtensions/ in elthasync.kext  do a move. first made a directory in /Volume/Machine HD/unsupported, the mv the kext problem file. I did move rather than  delete , in case  Mac needed it.
 
Removing  kext files did not work for me.  Found still had to perform a   kextcache -update-volume command   found  here:
http://www.tonymacx86.com/mountain-lion-laptop-support/105313-kernel-cache-issue.html


END
El Capitan itself, was not worth the upgrade. I'm not finding anything to 'brag about'. I did decided to do the upgrade because had Lion and did not upgrade to Yosemite. I did not want to get locked back where future upgrades wont work on Lion.  I'll keep  El Capitan not update until 2 years, LOL