This chapter starts very abruptly. It continues chapter 11, after a fashion, because it begins the story of Abram, but it does so very suddenly, with "Now the LORD said to Abram". First, when it says "now the...", know that this is one of those Hebrew connector phrases I talked about before. They interject this to make up for how there is no punctuation, and use phrases like this to separate different paragraphs/stories.
Second, one of the keys of the story of Abram is to study the different experiences he has with God. In particular, look not just at what God says, but just as importantly, look at how God reveals himself to Abram. In this case, it says "the LORD said". This doesn't necessarily mean that Abram heard an audible voice, but it means that somehow God communicated this particular idea/instruction to Abram.
Third, note the immediacy of Abram's response. While the story doesn't give a timeline (so this could indicate time compression like I discussed in chapter 3), just after verses 1-3, it says that Abram went forth. However, this is something we will see as a recurring pattern in his life, so it is possibly implied here as well.
So verse 1 is interesting. In some ways it is reminiscent of chapter 1, "In the beginning God created". It begins the story by stating an act of God, which is the driving force for what follows.
In terms of what God says, the command emphasizes leaving the familiar and this implies a lot of risk. Generally speaking, the ancient Mid East was a very family-centric place, as we will learn repeatedly by reading the OT. And in fact, Israelite culture in particular strongly revolved around the concept of the "inheritance", a given patch of land which is cultivated and passed on from generation to generation. So for Abram to give up his country and his father's home certainly seems to draw a strong contrast with the Israelite inheritance. It would also be dangerous to leave the familiar, because of how the family plays a strong role as a support structure. Living in a time when there is no government assistance, no food stamps, no public clinics or emergency room that is free for all to enter, your family plays the primary role of supporting you if something goes wrong, like you get injured or a business venture fails for some reason. So leaving all of that support and going off into unknown lands is a pretty big risk.
But on the other hand is the commensurate blessing, of becoming a great nation and his name being great. And then the last part is an ancient fealty oath, which Abram (and possibly the Israelites when reading this story) would understand. To bless those who bless and curse those who curse is a standard formula for expressing something like allegiance.
This is further regarded by many as the Abrahamic Covenant. Many people consider it to still be in effect, which has resulted in a notable "Bless Israel" community in the Christian world. This community (spearheaded by individuals such as John Hagee) believe that if they "bless Israel" by prayer, financial giving or political support, that they will receive a blessing, as per verse 3.
As I said before, Covenental theology is a whole field in its own right, so I'm not going to go into much depth here. But I will say that my personal opinion towards that viewpoint is hesitant, but not dismissive. It always seemed like this position requires you to latch onto this single verse absolutely, but I don't see how it can be reasonably reconciled with things like the Babylonian exile or Romans 11.
I guess what I will say in response is that this verse only explicitly declares a blessing on those who bless Abram. So it doesn't say anything here about "blessing those who bless your descendants" (though admittedly that could show up in one of the later blessings and I'm just forgetting it). And then there is the broader question of "what is a blessing", and there is the important question of whether it is accurate to interpret this passage literally when it is a formulaic statement of allegiance. And then there is the very important question of "which descendants we should include", when you consider passages like Galatians 3:16 where Paul positively identifies the seed of Abraham as being the Christ. I have never seen a cogent synthesis of all of these issues into the Bless Israel paradigm, but I'm still open to hearing such a synthesis.
We will hit verses relevant to this issue later, so I will probably discuss it more then. All that for just the first four verses... this will be a long post I see.
It talks about Abram's journey to Canaan (both a land and a people). And the Canaanite was then in the land. In verse 7, it says the LORD "appeared" to Abram. The first time, it was the LORD "said". Now he appears. This clearly shows an escalation of divine manifestation. Furthermore, it is getting somewhat more distinct. It describes a specific occasion where God appeared to Abram, rather than a general, broadly phrased message. The message in v. 7 is directly related to the prior message. The previously unnamed "land which I will show you" is Canaan. However, given the expression it is definitely possible that v. 7 shows a compressed conversation. I.e. that God says a whole bunch of stuff, but it is briefly summarized as "this is the land I was talking about." Of course, in my own conversations with God I have definitely seen the Lord use this sort of terseness, so I would not rule it out, yet the structure of ancient writings tends to encourage this sort of brevity, and we will see it often.
Abram's response again immediately follows the appearance of the LORD. He builds an altar at the place where the LORD appeared to him (which reinforces the notion that this is a distinct event, because it occurred at a single place). It isn't stated exactly where this happened, although the previous verse mentions Shechem, which in modern Israel is somewhat north-easterly, in the West Bank territory. Next he camps near Bethel, which is also reasonably near the west bank of the Jordan. He builds a second altar (definitely pious), and then starts traveling south toward the Negev (desert).
"Now there was a famine". This again implies a temporal disconnect. The famine occurs some unspecified time after Abram moves in and builds the two altars. Then Abram moves to Egypt. This is another very common trope in the Bible: fleeing to Egypt for refuge. It happens at least twice more in the OT and once in the NT.
I'm not sure what to say about vv. 11-12. I guess it was common to kill people and steal their wives in antiquity? I have no insight for this part. Then Pharaoh takes his wife for himself, gets struck with plagues, sends her back and drives them both out of the country. How did he know that Sarai was Abram's wife? It doesn't say. This is a strange story and I can find little to draw from it. It obviously shows vast cultural differences between then and now (given that Pharaoh just "takes" Sarai and gives free stuff to Abram in exchange), and it leaves a lot of open questions, but it at least seems pretty consistent, so I'd just take it as an element in Abram's life, something to see his character through, and move on. We can only imagine the famine is over, so in spite of Pharaoh's anger, Abram makes it through pretty well.
It is at first glance very weird that God would plague Pharaoh because he took Sarai. I mean, what the heck? It's the sort of thing I would write more about if I had more time to do this, but I will be focusing a lot on the next few chapters so maybe I will come back and write in some lengthy editorial at a later date.