It is still illegal to sell pot. It is illegal to give pot to a person under 21.
Persons under 21 are prohibited from all activity involving pot.
If you are negligent, while impaired from smoking, and harm another, you can be
sued for damages.

Your employer can restrict use of cannabis at the work site, and even prohibit
use off hours if you are given a drug test as part of your employment and there is
evidence of use.

Your landlord can prohibit use of cannabis in your home and on your property.

Despite the new law legalizing the use and possession of pot, there remain
criminal penalties for possession of pot with the intent to sell. However, the offense was reduced to a misdemeanor. Officers will arrest for this offense if one is carrying an amount over the permitted limits, or the pot is packaged in such a manner as to indicate you are selling. The burden is on the prosecution to prove the intent to sell; but they are proficient at raising negative inferences from the circumstances, so just do not engage in selling. This provision was left in the law to discourage the black market of pot, so that the new businesses will have a fair opportunity to prosper and the State will receive the taxes due under the new law.

Health and Safety Code 11359, 11360, 11361.
The misdemeanor punishment for possession for sale, transport, import, will be county jail for not more than six months or by a fine of not more than $500, or both. If the offender involves a minor in the prohibited conduct, or has a prior serious/violent felony conviction, or prior marijuana convictions, the punishment could include a prisonsentence.

Health and Safety Code 11361.8.
Anyone with a prior felony offense for possession for sale, now reduced to a
misdemeanor, can petition the court to recall and reduce the felony to a misdemeanor.