I'd normally be soo against this and anyone who doesn't believe me, i don't blame you, i'd probably be the same in your situation but i hae 2 stories:
When i was about 11 the guy across the road died, i never spoke to him but he always used to wave at me and take his hat off. A few weeks later I saw him walking past my house and waving and taking his hat off, my mum also saw it, crazy.
The other one is that when my aunty was pregnant with my cousin, she was worried because it hadn't developed enough and the doctors were worried. She went home from the scan and she saw my grandad (who i never met and died about 5 years before this incident), he said that the baby will be fine and born on the 7th of January, true to his word, it was.
Still don't fully believe in ghosts but think there is something we don't know going on