Streamline to the maps tips?

What are some lesser known tips when playing this game to boost past content?

Are there side quests we should ignore?

Should I skip past mobs if they're normal rarity and not blue/gold/orange?

Skip doing vaal temples?

I only got in the last two weeks of the last season and I feel like my campaign time is 10-20+ hours. Is it my essence drain skill? Did I pick a bad starter class?

I have only dropped one of the currency that gives 4 gem sockets and need to power through to get more of those faster I'm feeling.

What are some of your "must do this" tips you never skip?