Get a lot of serums, like maybe 50, before dealing with anything other than the super basic quest line stuff, easy to do it early on when ur less sus, and less consequences for a fuckup you just restart early.
When getting Serums, keep an eye on suspicion, whenever it's high you need to work or take your break to lower sus. (keep in mind missing the whole day of work=more sus)
doing suspicious things at different times of the day lead to different levels of suspicion game.
once you get a bunch of serums, and mind control your roommate, landlord, and boss, make a save. (keep in mind if you fuck up you can always go back)
then you just open the journal for your tasks (each individual has different tasks required, you do them to progress), later on there is a way to automate making serums, earning money, doing research, and it raises sus, so the dev also added a way to auto reduce sus. Make sure to take advantage of these things.
Past that things just kinda snowball, keep an eye on sus, and just do the tasks.