Back in the dark ages, I was taught to rinse the flask to get the remaining crystals onto the filter, not with fresh solvent, but with the mother liquor that had already gone through the filter. That way, the solvent you are washing your crystals into the funnel with is already saturated with your compound. Once all of your crystals are actually in the funnel, then you can wash them with some fresh cold solvent, just to make sure you have washed away any solvent containing impurities that might be sticking to the crystals.
If you have the foresight, saving a few seed crystals is a far better method of seeding your flask than scratching the glass. Opsomath's advice on nucleation is good - just let it cool slowly to room temp. If the solution starts to turn cloudy and you don't see any crystallization, that would be a good time to add a couple of tiny seed crystals - that might mean your compound is starting to come out of solution but hasn't yet begun to nucleate.
Again, back in the dark ages, there was a story that went around about a famous chemist (the name changed depending on who was telling the story) who dipped the tip of his beard in any solution he was crystallizing. If no crystals formed when the solution cooled, he would shake the end of his beard over the flask, dislodging the seed crystals that would have formed as the solution evaporated from his beard and seeding the flask. You can do the same thing by stirring the hot solution with a glass rod, taking it out, and waving it around gently until the solvent evaporates. This will usually leave you with some useful seed crystals on the end of the glass rod.