There are hundreds of promises from God in the new covenant. It's a little overwhelming to make a list. What God is looking for from us is repentance from sin (Mt. 1.17), believing that Jesus is God and has died for our sins and rose from the dead (Rom. 10.9), and following Jesus (Mk. 8.34), which means you will love him and obey him (Jn. 14.15). What you get for that is forgiveness, which is freedom from your sins (Rom. 6.17-18) and eternal life (Jn. 3.16). That's what Christianity is all about.
SOME of the promises of the new covenant (these just from the first half of the Gospel of John):
- spiritual light (Jn. 1.9): understanding of spiritual truths (Jn. 1.50; 8.12)
- you become a child of God (Jn. 1.12): belonging as members of his family (Jn. 3.5)
- grace from God (Jn. 1.17)
- truth from God (Jn. 1.17; 3.21; 8.32)
- accurate knowledge of God (Jn. 1.18; 4.23)
- forgiveness from our sins (Jn. 1.29). You will not need to be plagued by sin and misunderstanding (Jn. 8.12)
- filling of ourselves by the Holy Spirit (Jn. 1.33)
- see the kingdom of God (Jn. 3.3)
- escape from eternal punishment (Jn. 3.16). You will not face the judgment of God (Jn. 3.18; 8.24; Rom. 8.1)
- eternal life (Jn. 3.16; 4.14; 5.24, 28; 6.27 and many more)
- you will have the power of God in you (Jn. 7.38)
- You can know God (Jn. 8.20)
- spiritual protection (Jn. 10.7-10, 28-29)
- Abundant life, even now (Jn. 10.10)
- You will see the glory of God (Jn. 11.40)
- God will honor the one who serves Jesus (Jn. 12.26)