One of the trickier German verbs, mostly because the grammar is different to the corresponding English phrase.
Tips:
- if you make a mistake, read the correct version out loud (even better: twice)
- don't be afraid to make mistakes, you can always repeat the game
- for extra learning effect: speak/write some other sentences with the nouns exchanged, as long as plural / singular stays the same, so does the sentence. E.g.:

die Lampe - "Wie gefällt Ihnen die Lampe?"
der Tisch - "Wie gefällt Ihnen der Tisch?"
der Wein - "Wie gefällt Ihnen der Wein?"
das Wohnzimmer - "Wie gefällt Ihnen das Wohnzimmer?"