After the call to unity in 1:27-30, Paul tells us the logical and practical ways we can achieve Christian unity. And all of these have to do with our mindset.
Mindset (1-2): Paul calls believers to first consider the benefits that they have received from God: "encouragement in Christ," "consolation of love," "fellowship of the Spirit," and "affection and compassion." These all point to spiritual blessings from God. These are expressions of "love" (2:2) from God, and we are called to extend "the same love" toward one another. We are to consider how God has treated us, and we are to treat others the same. All of this requires the involvement of our minds. So, Paul points out we are to be "of the same mind." We must give thoughtful consideration to God's love toward us. It is with this mindset that we maintain "the same love."
Christian unity comes about as we reflect toward others God's love. This is the way to become "united in spirit" and "intent on one purpose." This shows us unity isn't achieved through doctrinal agreement alone (though necessary!). It also requires that we relate to one another with God's love. When we see and treat each other as God sees and treats us, we begin to exhibit Christian unity.
Actions (3-4): Paul continues this thought in 2:3-4, and points us to two sets of contrasting actions. The first set deals with why we do what we do. The motive for our actions should never be "selfishness" or "empty conceit." The former speaks of "selfish ambition" much like the one mentioned in 1:17. The latter is literally "vainglory" or "empty glory." We should never seek our own exaltation. Instead, we are to "regard one another as more important than yourselves." Importance here has to do with value. In our sinful flesh, it is a knee-jerk reaction to regard ourselves as the most valuable: our own satisfaction, well-being, dignity, pleasures, comforts, etc. But we are to see others as more highly valued than ourselves. This means we promote others' satisfaction, their well-being, etc. above our own. The second set points us to a question of honest self-evaluation: whose interests are we really looking out for? We are called to give attention to the interests of others.
Example of Christ (5): Paul then points us to Christ who fully exemplified this attitude. He gave Himself up in pursuit of the Father's interest, even becoming "obedient to the point of death, even death on a cross" (2:8). It is this attitude of Christ that we are to have etched into our minds. This Christ-like attitude is what ultimately produces Christian unity among God's people. Therefore, Paul calls us to habitually consider the selflessness of Christ, and this is what he will develop in the next section.
 Logical progression seen in "Therefore" of 2:1. Practical seen in the specifics of 2:1-4.
 Paul frames this as "make my joy complete." He would be thrilled to "hear" (1:27) such a report.
 Paul assumes they did in fact receive these benefits. The Greek first class condition shows "if" is more like "since." The certainty of these benefits shows that these come from God (not all saints receive affection from others!). Also, "encouragement in Christ" and "fellowship of the Spirit" point to God as the source.
 This is best understood as fellowship with God the Spirit. In the NT, the genitive with koi-nō-nia (κοινωνία) repeatedly describes the object shared. When applied to people, this describes fellowship shared with the person mentioned. Cf. 1 Cor. 1:9 where this is the case: "fellowship with His Son."
 The last two benefits form a couplet and unlike the rest (which are singular), these are plural in the Greek. These two form the catchall category of what warmth believers receive from God.
 The imperatives of 2:3-4 are participles in Greek and 2:1-4 grammatically form a single sentence.
 This structure is reflected as follows: "do nothing … but …" (2:3) and "do not … but …" (2:4).
 The Greek word in 1:17 is the same word in 2:3—e-ri-thei-a (ἐριθεία).
 This is the compound word ke-no-do-xi-a (κενοδοξία) which is "empty [κενός]" and "glory [δοξία]."
 The word for "more important" is hu-per-ech-ō (ὑπερέχω) which means "to surpass" or "to rise above."
 The Greek verb is imperfective and describes an ongoing observation, to pay attention to something.
 The verb phro-ne-ō (φρονέω) was used in 2:2, "being of the same mind" (lit., "thinking the same thing").
 The imperative of this verse is imperfective and describes an ongoing, continual action of contemplation.