How to earn lifestyle points (yellow)

 “LPs” is short for life style points  :) 

Every time you’ve achieved all collectibles, you need to empty the collection card by tapping “Start new accessories collection”. Then let your Sims continue cooking, fill the collection card again and get 5 LPs.

Regarding the profession workplaces it may help to look at the blog by the EA Creator The Girl Who Games: 

https://thegirlwhogames.blog/2017/09/01/the-sims-freeplay-profession-careers-police/

Hi, Im talking about the yellow lifestyle points... I got my sims to cook cheese and tomato toast over and over again but there is no gain in the lifestyle points... its the yellow colour diamond one...

Hi thank you so much for your reply, sincerely appreciates it. For the workplace, yes I do accompany my sims, and usually there will be resource once they complete one task, but I collect these resource and not knowing how to use them, I didn't know you can use resources to build departments...

You can earn LPs by having Sims doing hobbies like cooking. Use as many Sims as you can and let them cook cheese & tomato toast again and again. After completing the collection card, you’ll get 5 LPs. Then reset the collection and start over. As soon as your Sims have reached level 6 in cooking, you’ll get 1 LP per Sim. Then let them do a short different hobby once and then start over with cooking. All this sums up.  

You don’t have to use LPs to get the workplaces done. Accompany your Sims while working there to earn coins and the needed resources. Use coins to enlarge the storage and/or trade them in for missing resources.   
  
Hope, this helps :)