Chapter 18 resembles an interlude in the main story Verses 1-2, tells of the arrival of Jethro with the wife of Moses and his sons, and Jethro's sharing of a sacrifice and a meal. In verses 13-27 we have Jethro's practical advice regarding the division of responsibility, and Moses acting upon it.
Some of the main lessons of the chapter are:-
Jethro was a descendant of Abraham (Genesis 15:2 ). He was a heathen priest of Midian. Probably all knowledge of the true God was not lost on him. Moses' life and conduct no doubt affected him. Certainly what he heard of what God had done for Moses and Israel, brought him to see for himself. What the Lord has done in His redemptive work in Christ Jesus in our lives should make Him attractive to those in our families who know Him not. The report of what the Lord Jesus did, went out into all the land (Matthew 9:26 ), to hear of His power to pardon (Matthew 9:2-28 ), power over death (Matthew 9:18- 26 ), power over disease (Matthew 9:20-22 ), is so attractive to the needy lost.
With the coming of Jethro we learn that Zipporah, of whom we have not heard since (Exodus 4:46 ), objecting to circumcision, Moses had sent her back to her home (Exodus 4:2 ). Now she returned to her husband (Exodus 18:6 ). The courtesy, humility, obedience and affection of Moses is an example for us to follow.
1 Peter 3:8 "Finally, all of you be of one mind, having compassion for one another, love as brothers, be tenderhearted, be courteous."
Being moved by Moses speaking of what God had done for Israel (Exodus 18:8 ), Jethro rejoiced (Exodus 18:9 ), even though he was not part of redeemed Israel he offered a sacrifice to God (Exodus 18:12 ). That this was acceptable is shown by Moses being joined in the accompanying meal by Aaron and the elders of Israel (Exodus 18:12 ). In like manner financial offerings or sacrifices can be accepted from those who have not at the time, committed themselves to Christ. Believers can freely accept hospitality of unbelievers.
1 Corinthians 10:27 "If any of those who do not believe invite you to dinner, and you desire to go, eat whatever is set before you, asking no questions for conscience sake."
Even financial gifts can be received, when accepted applying the truth,
1 Corinthians 10:26 "for the earth is the LORD'S, and all its fullness."
The money belongs to God and the hearts of unbelievers are in His hand. The main purpose of kind acceptance of the uncommitted's sacrifice and hospitality is brought out in Numbers 10:29-32, where the opportunity is taken to invite Jethro, called there Reuel, to join them.
Jethro witnessed Moses bogged down in adjudicating civil cases (Exodus 18:13 ). He suggests the using of qualified help. It is important to notice that Jethro's advice (Exodus 18:21-22 ) is qualified by the words of,
Exodus 18:23 "If you do this thing, and God so commands you, ..."
Jethro knew that what he advised could not succeed if it was not in harmony with the will of God. Verse 24 tells us that Moses took the advice, no doubt having the divine approval (Exodus 18:24-27).
These are given in,
Exodus 18:21, "Moreover you shall select ... able men, such as fear God, men of truth, hating covetousness;"
That is, those of natural and spiritual ability - those who reverence God - devoted to His Word and ways - those who are men of integrity, honest and honourable - above selfish interests. No desire, aim, ambition or lust must corrupt service to the Lord.

In relationships with unsaved relatives, what do you learn from the example of Moses?
How did Jethro qualify his advice to Moses?