I really like to finally dilute my perfumes to perfume strength of at least 25%. That is: 25% of the perfume composition in 75% alcohol. You can safely experiment with other dilution ratios though. To give you an estimate on ratios used in industry:
15% - 30% : Perfume, also named Soie de Parfum at 15% - 20%
10% - 15% : Eau de parfum (#EDP)
7% - 10% : Eau de toilette (#EDT)
2% - 7% : Eau de cologne (#EDC)