IMHO nowadays people became less romantic, few of them make really soul-touching deeds and presents… However, if you want to please your girlfriend, my idea is just for you!
Agree, if you simply say "I love you" it would be nice, but cannot bring so much emotions as if you make something really special! First of all, record personal music or song for your beloved! No doubt, if you cannot play any instrument yourself, make use of the record services - just explain what melody you would like to hear and then lay your loving message on it… If you compose some verse, describing your emotions and feelings it would be perfect at all. So, the song or melody with your message is ready! Now buy a jewel and again, make it personal - scratch some words on it - I love you, For my darling, You are my life, and so on…
So, now your declaration of love will be really memorable and beautiful! Arrange romantic evening and gift these presents during it!