Welcome to the BA forum.

To gain BA status the quick way is to fly in premium cabins. Flying long-haul in economy does not rack up many Tier Points for status purposes. The same applies to any airline, not just BA. Two long haul flights in economy or premium economy is really not a lot of flights to be considered a frequent flyer.

The thing to ask yourself is what you are after.
Free flights? Best way is to get a BA American Express card to earn Avois points. Shop at Tesco helps too. Many on this forum have learnt to earn free flights without actually flying BA on paid flights.

Gain lounge access and book seats for free? Look out for BA Premium sales and see if there are reasonable Club (i.e. Business class ) fares going.
One ET return to Europe earns 20 TPs
One CE return to most Europe earn 80 TPs
One CE return to Helsinki or Istanbul earns 120 TPs
Thats is where the multiplier effect really kicks in.