If you're referring to the popular Sentiero Azzurro (former No. 2) trails, you can easily hike them on your own. They're easy to follow and there will be lots of others hiking with you. Note that a Cinque Terre Pass is required to hike those specific trails, which you can easily buy when you arrive there. No passes are required to hike the many other trails in the area.
It's important to note that at the present time, the No. 2 trails from Riomaggiore to Manarola (Via dell' Amore) and from Manarola to Corniglia are closed and likely won't re-open this year. You can however still hike from Corniglia to Vernazza and Vernazza to Monterosso. Note that when you arrive in Corniglia by train, you'll have to climb lots of stairs to reach the town (where the trail starts). You can take the small shuttle bus up the hill for a small fee, unless you have a Cinque Terre Treno card, which I believe covers that.
There are two "schools of thought" on which end is better to start from. I normally prefer starting from Monterosso as that's the most challenging section. There's quite a climb at the beginning, and I find it easier to go up steep hills rather than down. The stretch from Vernazza to Corniglia is slightly easier. You can easily use the local trains to bypass the sections of trail that are closed.
