Aiming to be a vagabond can be quite difficult if you're going to do it by yourself. Grinding for EXP as a Beginner should be done with a party as the Beginner class can only equip only a select few weapons and armors and not to mention their stats are not high compared to the other 1st class jobs available.
To be able to change into a Vagabond, the Beginner should reach a level of 115 and a Fame around 20,000 up to 50,000above (or the status of a Citizen up to Greenhorn).
•Talk to the Beggar and select option 1. He will ask you if you are enjoying your adventure. Select the answer "Still Drifting".
•Keep on choosing option 1 until the Beggar introduces the Vagabond Job to you.
•He will need to test you first so he's going to ask 3 questions.
1st Question is: "What is the name of the leader of the Balie Church?" --Aleister
2nd Question is: "Who is a Level 500 Bale, the strongest one?"--Anastasis
3rd Question is: "Guess who will win if 100 Piyas and 10 Rascal Rabbits had a Guild War?"--Tie
•After getting all the correct answers, he will present to you the portrait of Baldea. Just continue the conversation until you reach the end.
•Finish all the conversation and you will now be changed into a Vagabond. To learn Vagabond skills, just talk to the Beggar again.
Please refer to this Wiki page for the Vagabond Skill: VAGABOND SKILLS