Since I didn't find anything about it, I decided to create it... Better late than never...
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Level Requirement: 5
Receive the 1st star Dragon Ball quest by accepting the quest from this Namekian:
Level Requirement: 7
Receive the 2nd Star Dragon Ball quest by accepting this quest from this Majin:
Level Requirement: 9
Receive the chain starter quest from this Namekian. Kill 7 Red Pants dogs.
After deliver the quest, he'll give another one. Take it to Azuza Watchtower Village.
Then receive the 3 star Dragon Ball quest from this namek.
Level Requirement: 12
Receive the 4th Star Dragon Ball quest by accepting this quest from the Namekian in front of Dragon Cave.
Level Requirement: 14
Receive the 5th Star Dragon Ball quest by accepting this quest from this Namekian Healer.
Level Requirement: 16
Receive the 6th Star Dragon Ball quest by accepting the chain starter quest from the Namekian in front of Map Revealer. You need to kill 9 Putrid Saibaman.
After you have completed, receive another one from the same NPC. Kill 7 Snakes and it's King Snake.
Complete it and he'll give the 6th star Dragon Ball quest.
Level Requirement 20
Receive the 7th Star Dragon Ball quest by accepting it from Super Kami Guru Grand Elder Guru.
And that's all. Just put the Dragon Balls (in any order) and summon Shenron.
You only get 1 wish by this set of balls.
Credits: ishali (dbocom) , [English] Human Dragon Ball Quest Guide by Kruxifer , [English] Majin Dragon Ball Quest Guide by me