Probably the greatest obstacle you will face in going deeper on the parable of the four soils is that what you already know is likely wrong. Parables conceal, not reveal! France says that modern readers think of parables as helpful illustrative stories, so they miss the point that parables mean nothing until they have been explained.
Keep in mind that the things Jesus teaches in this section come just after being accused by the Jewish religious leaders of doing his mighty deeds by Satans power. On that same day, these events unfold.
1 That same day Jesus went out of the house and sat by the lake. 2 Such large crowds gathered around him that he got into a boat and sat in it, while all the people stood on the shore. 3 Then he told them many things in parables, saying: A farmer went out to sow his seed. 4 As he was scattering the seed, some fell along the path, and the birds came and ate it up. 5 Some fell on rocky places, where it did not have much soil. It sprang up quickly, because the soil was shallow. 6 But when the sun came up, the plants were scorched, and they withered because they had no root. 7 Other seed fell among thorns, which grew up and choked the plants. 8 Still other seed fell on good soil, where it produced a crop a hundred, sixty or thirty times what was sown. 9 Whoever has ears, let them hear.
In observing the Parable of the Four Soils, you must learn to carefully consider the context. You would be surprised how many questions can be answered by simply reading the surrounding setting of a verse or parable. And, if you learn to do this consistently, you will find that various Christian authors sometimes try to support their views by giving a Bible reference whose context tells you otherwise. This may not be intentional; they may simply be restating what they have read elsewhere.
In Matthew 11-12, we saw a lot of opposition to Jesus, and in Matthew 13 we find numerous parables, which mention the kingdom of heaven a phrase referring to Gods kingship in verses 11, 24, 31, 33, 44, 45, 47 and 52. It is reasonable to think that the Parable of the Four Soils deals in some way with both Gods kingship (as expressed in Jesus) and the opposition to that kingship. France explains that chapter 13 shows the disciples how Gods kingship can be resisted by his own people and sets the disciples expectations about the reception their witness will receive. But it does so using parables, a form that is not self-explanatory.
The Parable of the Four Soils is clearly important. Matthew, Mark and Luke use it as their first substantive parable, and it is one of only two parables that Jesus explains in detail. The reason for this primacy will unfold when I interpret the parable, but, for now, I will simply say that unless you obey this parable, none of the others will matter!
Kline Snodgrass prefers to say that this parable is a fourfold [resemblance] because it presents four instances of sowing only one successful followed by an appeal for hearing. Such parallels were common in the ancient world. As France observes, the way Jesus structures the parable forces the reader to think about obstacles to growth and not just about the happy ending.
Interpreting the Parable: Part 1
It is hard to imagine what thoughts might have been tumbling in Jesus mind as he left the house where so much had happened and walked to the lakeside where he sat down (verse 1). He had to know that a large crowd would follow him there. Because Jesus entered and sat down in a boat (very likely with his disciples) many more people would be able to hear what he said (verse 2). Perhaps they expected him to teach as he had before, not knowing that those days were done.
You may have noticed the repetition of the phrase went out in verses 1 and 3. Jesus uses a particular Greek verb (exerchomai) to picture the farmer going out to spread seed on his land (verse 3). In writing his Gospel, Matthew chose that same verb to describe Jesus departure from the house to go down by the lake. Matthew is probably trying to give a subtle hint that Jesus is the farmer sowing seed. Since Jesus separates his interpretation of the parable from its initial expression, I will do the same, but taking note of parallel language is part of your task in interpreting the Bible. Fortunately, the NIV translators preserved the parallel language in their English translation. That does not always happen!
By focusing on four different types of soil, the parable helps us see how the farmer was thinking about his crops yield. Even within the single type of soil actually producing a crop, the variation in yield was readily apparent. Jesus audience certainly knew about such different outcomes, but, although they might have some guesses, they did not know what Jesus was trying to say about these differences. Parables conceal!
Was it possible for Jesus opponents to use these words against him? If so, how? My answer is no, but, as I tell my wife, I was wrong once.(smile)
After declaring the complex parable, Jesus gave a terse command (verse 9). I am fond of the NET Bibles translation because it captures the force of Jesus words: The one who has ears had better listen!
 France, Matthew, 499.
 Snodgrass, Stories with Intent, 145.
 Snodgrass, Stories with Intent, 146.
 France, Matthew, 504.