Where should I start (based on my interests)?

To start, I have read the post about this on the FAQ. I have already been reading the wiki, and I have found some interests, so I am trying to see which of them I should use to break into the series and the novels. I will list these interests in categories (broad to specific) and rank my interest in them, so you have a better grasp on what I like for better detail.

Events

1. Horus Heresy

2. War in Heaven

3. Unification of Terra

Factions

1. Necrons

2. Tyranids

3. Tau

4. AdMech (though, more of the organization than characters. Meaning I am interested in what an Archmagos is, not Cawl.

5. Necrontyr

6. The Old Ones

7. C'tan

Groups

1. Sons of Antaeus

2. Marines Malevolent

3. Salamanders

4. Thunder Warriors

5. Iron Warriors

6. Sisters of Battle

People

1. Perturabo

2. Fabius Bile

3. Irda

4. Trazyn

5. The Silent King

Final Thoughts

I hope this isn't too common or easily answered. I was thinking about reading the Horus Heresy books, but that is a very large amount of reading (though, it would scratch Perturabo and Fabius). I also don't know which books to jump around for the others (though I think Fabius interacts with at least Trazyn?) Some of these are also minor characters in books (Sons of Antaeus) while some novels have multiple (Salamanders and MM). I figured people who have read these would know which is beginner friendly and which need more back ground info before enjoying, though, the wiki exists for that.