During your traineeship/apprenticeship you can get reduced-price monthly season tickets. If you decide to get an all-year season ticket, you save something like 20 % top of that.
Alternatively, if the firm where you are doing your course offers it, you can take advantage of the BonusTicket for apprentices/trainees, which is subsidized on top, so unbeatable value for money!
Tip: you will need an entitlement form to buy reduced-price tickets. This must be validated by the firm where you are doing your course and then by the relevant Chamber of Industry and Commerce/Crafts and Trade or verifying body. And when you travel by hvv, you should always have it with you.