να γράψω or να γράφω: the Aspect Choice

να takes TWO different verb forms and they do not mean the same thing. να + the perfective (dependent) stem - να γράψω - views the action as ONE whole act: «Θέλω να γράψω ένα γράμμα» (I want to write a letter, and then it is written). να + the present (imperfective) stem - να γράφω - views it as ongoing, habitual or repeated: «Θέλω να γράφω κάθε μέρα» (I want to write every day). It is the same choice you already make between έγραψα and έγραφα, and between θα γράψω and θα γράφω - only the particle in front has changed. Two practical anchors: a single, bounded act takes the perfective, and a few verbs SELECT the imperfective outright because their meaning is about duration - αρχίζω να, συνεχίζω να and σταματάω να are always followed by the imperfective (αρχίζω να γράφω, never «*αρχίζω να γράψω»). The perfective is the commoner of the two after να, which is why it is the one you met first, but choosing it automatically is how a learner ends up saying «θέλω να πιω καφέ κάθε πρωί» when they mean a daily habit.