Well, sunlight, fertilizer, and the appropriate amount of water are all a good start. They also appreciate nice conversation while you tend to them.

Forget-me-nots aren't particularly suitable as potted plants, either. You lived in Snowdin, yes? That may have been your first mistake. They like good, moist soil, preferably deep. You may have not watered them enough. You should try growing something more... forgiving... if you wish to have a houseplant. Philodendrons are particularly hardy. Mother-in-law's Tongue is particularly well-suited to being ignored indoors; it can go for weeks without being watered.