Condolences on your loss!
As someone said, not to die in a state of mortal sin - that is, unrepented, willful, deliberate sin, involving a serious matter.
Something that comforts me over my relatives is to think of the image used by C.S. Lewis in describing judgment: The person who has died comes face to face with the Lord Jesus. Either he loves Jesus on sight, because (whatever the person's individual failings, weaknesses, damage, etc.) he longed for truth, beauty, goodness, and holiness ... or he will hate Jesus on sight, because in his life he deliberately rejected all that Jesus is and represents.
The person who loves Jesus will at some point be united with Him in Heaven, perhaps after suffering purgation (cleansing from the effects of sin, and remaining self-love.) The person who hates Jesus when he meets Him will be unable to be near Him, ever.
Fishtank, sincere sympathy to you in your loss.
Tax-chick, I believe this is the C.S. Lewis section that you're referencing:
Lewis spoke of the need to be stripped of our filthy rags, scrubbed and made gloriously clean before we stand in the presence of God. As Lewis pointed out, we want to be cleaned up:
"Our souls demand purgatory, don’t they? Would it not break the heart if God said to us, ‘It is true, my son, that your breath smells and your rags drip with mud and slime, but we are charitable here and no one will upbraid you with these things, nor draw away from you. Enter into the joy’?
Should we not reply, ‘With submission, sir, and if there is no objection, I’d rather be cleansed first.’
‘It may hurt, you know.’
‘Even so, sir.’"