Should I now do 3 sets of 5 reps- or 5 sets of 5 reps?

5x5 is obviously better. 3x5 is more for beginners but your doing less work and getting slower results. Me i warm up with the bar usually , then depending if i feel like it i add two 25 on the sides , then go into my work sets . Get over to bodybuilding.com and learn more about lifting . This website won't help you too much