To get to Cinqueterre, you have to go to La Spezia Centrale. Cinqueterre is made up of five towns: Riomaggiore, Manarola, Corniglia, Venezza and Monterosso, the first one being the closest to La Spezia and the last the furthest. I recommend starting at Monterosso and then walking all the way to the first town, which is what I did. I reached Monterosso at about 10.30am and then I hit Riomaggiore by 7-7.30pm at an average pace.
The walk from Monterosso to Venezza is the most strenuous and takes about 2 hours, which is why I suggest this to be your first walk. If possible, try not to eat lunch at Venezza as the price is at least €2-3 higher than what you can find at Corniglia. If you ever eat at Venezza, do not eat the recommended Pesto Pasta! It totally sucks, even though they say that it is a delicacy of Venezza. From Venezza, it takes 1.5 hours to walk to Corniglia. While the path is not as steep as the previous one, certain parts have very rocky terrain.
From Corniglia, it is less than an hour's walk to Manarola. When I went in April 2014, the easy path (the 1 hour path) was closed as there was a landslide that destroyed part of the path. Nevertheless, it is still doable and you just have to be careful and move slowly at the landslide part.
Manarola is the prettiest city out of the 5, and many would agree with me. When you google Cinqueterre, the beautiful pictures that you see are actually of Manarola.
From Manarola, it is an hour's walk to Riomaggiore. We made the mistake of eating dinner at Manarola, so we did not manage to walk to Riomaggiore as it was already dusk. However, the walk takes about an hour and should be quite manageable. There was a 20 min path that was closed off, so if you can take that it is even faster.
From La Spezia Centrale, I continue to head down to Pisa to see the leaning tower. About an hour's journey and note that you should go to Pisa San Rossore and not Pisa Centrale as the tower is much closer to the former station. There is nothing much to do in Pisa other than taking funny pictures with the tower and seeing the Duomo next to it. Definitely the most boring town in my Italy trip.