1. Move all the fish to a new home (i.e., bucket)
2. Empty the water of the 35L tank to as little as possible
3. Move the substrate & plants, and attach filter
4. Move the old tank from its current perch, and move the new tank there
5. Fill new tank with a bit of the old water
6. add dechlorinator
7. Top off with new water
8. And then reintroduce fish
The changes I'd make, but more or less the same.
"I was also thinking of adding a piece of driftwood into the tank - how do you guys prepare this?"
Pick it off the beach/river and throw it in tank, maybe wash the sand/dirt off