As others have mentioned, you will need to fly about four roundtrips between SIN and Germany in order to qualify for a level of status with meaningful benefits in any major program. More when you fly on very cheap fares.

Mileage expiry will be an issue: all programs except BAs Exec club which follows the US model where account activity extends expiration of all miles in an account have hard expiry policies where miles expire after three years. This can be mitigated with co-branded credit cards: Both LH Miles and More as well as Airberlins topbonus' programs waive mileage expiry for certain co-branded credit card holders (M&M only for holders of a premium card with higher annual fee, topbonus only for medium- and top tier status holders)
Airberlins credit card also lets you earn status(!)-qualifying miles for cc spend and even cash advances, which is unique among European programs.
Also, all programs have greatly devalued their earnings for discount economy fares. Generally, one does not earn much anymore when just flying on the cheapest fares regardless of the program.

Personally, as you'll be living in Germany and fly less than 50k miles in discount economy, I`d focus on co-branded credit card activity for mileage accrual and status earning. The best programs for this are LH M&M and AB topbonus, with a nod towards topbonus because their cc lets you earn status miles - which will pretty much be your only chance to earn mid-tier elite status on a major alliance (oneworld).