The toughest skill to max is photography. First, purchase the "Snapshot" Ascension to take photos during combat. This costs one Tech Bar. Purchase "Tech Strike/Tech Damage/Quick Tech" to recharge your Tech Bar faster. To fully max this skill, you will need to take pictures during all combat encounters, every time Prompto gets a Tech Bar. This will take a long time, but there is a quicker way. Put a rubberband around your Analog-stick and controller to automatically walk around. Leave the game on for hours. Check back once an hour to rest the party or make sure you are still moving around and have not gotten caught on something. Prompto will take pictures approximately every 3 minutes, or 20 pictures per hour. You need approximately 1,200 pictures to max out your photography skill.