DO you have any good guides with tips and tricks, that allows to know the best way of skilling and lvling?

that is incredibly vague. I'm sure there are plenty of guides for every skill on Youtube that you could use.

Kinda going off of what abra said, you can look up many great things. If you search EHP (Efficient Hours Played) you will find a lot of information on said things, seeing as you didn't state whether or not your question particularly pertains to speedrunning... I will also add that you could look up runs of others and see what they did to effectively get their skill requirements quickly.

On one final note, I will add that most efficient gains are, and have been for awhile now calculated through the use of alts and playing multiple characters at the same time to gain optimal EHP rates.

In some cases, quests can be very good. Can look on the wiki at the list of xp rewards. And yes, during lower effort activities, like agility and bank standing skills like herblore, I run 2 alts for money to fund my buyables.