If you decide to go for a stroll along the beach and walk north - do not walk past the Point Hostel (day or night) as this is an unsafe area for tourists. A friend of mine forgot being told this and walked past the hostel and was robbed by some teens with bolt cutters (he had about 7 soles on him so just handed it over).
Also after hitting some clubs a friend and I wandered along the beach and sat down to just chill and look at the stars when after a while we were approached by police and told it wasn't safe for tourists at night just there (muggings). If we were closer to the light of the clubs it would have been alright (the area of the beach we sat at was near the bridge as you enter Máncora - but close to the water).
The beach during the day/sunset was fine, no problems at all.
I personally never lost anything on the beach or had anything stolen or felt I was in any type of danger... but just be mindful.
Tuk tuk drivers are notorious for trying to rip you off. I was told before arriving that getting to my hostel would cost no more than 1 or 2 soles. My tuk tuk driver agreed to 2 soles and off we went. On arrival he said 'No, 5'. I gave him the 2 we agreed upon. When taking a tuk tuk try to make sure you have exact change and don't use notes.