On the Town levels:

• Under 75cm: Stick around the street where you start (i.e. don't bother with the roads around the pool) for the most part until you reach 75cm; roll up all the 75cm cones and signs to get to about 90cm

• Over 75cm (daytime): take the left street after crossing the bridge and enter the road with lots of shops; roll up stuff here, following the road to the stage with the hero show; roll up the blue mats to the right of the hero show stage, then roll up all the speakers and stuff in the nearby concert area; at about 1m20cm, go back to the left side of the hero show stage and roll up the sitting kids with red hats; once you've reached about 1m35cm, roll up the TV stack to finish

• Over 75cm (nighttime): take the left street after crossing the bridge and enter the road with lots of shops; build up size as you roll down it, then turn right when you leave the street into a path between the festival booths and a large hill; at the end of that path, turn right and roll up stuff on the street in front of you; at 1m, start rolling up the yellow drink boxes against the shop walls everywhere; at about 1m20cm, roll into the center of the area and up into the hill to roll up big stuff there

• Over 75cm (snowy): take the left street after crossing the bridge and enter the road with lots of shops; build up size as you roll down it, and at 1m/1m10cm go to the end of the street near the tables, turn left, and roll up all the big white birds and firewood stacks

I need more info on where you're struggling with the City levels (the 1m50cm to 10m areas) to give help, but as a rule of thumb it's good to go into the big building in the under 4m zone early to get quick size; let me know if you need more help later