There are several things in which all believers should participate.
                   
1.Read The Bible

The believer should read and study the Bible. The Bible is God's Word to humanity, His communication to us.

Blessed is the person who walks not in the counsel of the ungodly, nor stands in the path of sinners, nor sits in the seat of the scornful; But their delight is in the law of the Lord, and in His law they meditate day and night (Psalm 1:1,2).

By reading and studying the Bible we can know what God requires of us.
                                         
2.Pray

By reading the Bible we have God talking to us prayer is our talking to God. Jesus had this to say regarding the importance of prayer:

And I say to you, ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you. For everyone who asks receives, and the onewho seeks finds, and to one who knocks it will be opened (Luke 11:9,10).

3.Assemble With Believers

The Bible commands believers to meet with one another.

Not forsaking the assembling of ourselves together, as is the manner of some, but exhorting one another, and so much more the more as you see the Day approaching (Hebrews 10:25).

This is necessary so that we can draw encouragement from one another.
                                    
4.Tell Others The Good News

Finally, it is the responsibility of the believer to tell others the good news about Jesus. The Gospel according to Matthew closes with these commands of Jesus.

All authority has been given to Me in heaven and on the earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age (Matthew 28:18-20).

Summary

Bible study, prayer, assembling with believers, and telling others: these four things should be the practice of all believers.