Thank you! Tried to follow your advice and successfully killed invading groups in three games:
- https://online-go.com/game/12028561 (already over, invasion was from moves 116-148)
- https://online-go.com/game/11986856 (almost at counting stage, moves 156-180)
- https://online-go.com/game/11998083 (still in progress, move 108 onwards but confident White left dragon is dead).
Update: My ranking was about to stabilise at 20 kyu, but seven wins in a row (including one timeout and three early resignations) pushed me up to 17 kyu. That feels too high; I think I am still playing like a TPK rather than a DDK and am trying to figure out my true level to choose suitable study material. One very close and entertaining game was https://online-go.com/game/11925098 which teaches to never take life for granted!