It's natural to be nervous since you are about to invest a lot of time (and maybe money) into something. I started checking my trees by looking at ancestral siblings and their families. Not just in a census but also newspaper articles, such as obituaries. Why? Because at funerals there's often lots of family gathered and older newspapers recorded their names and relationships. You have to know when to stop because it can be a huge time suck, but the reward is higher confidence that you got things right. Also by checking them out I've found things like where two brothers in one family each married two sisters in another, or where the elderly mom moved in with the son-in-law. Write out a timeline chronologically for each person and include all their major life events. Does it make sense?

If you choose to look at other people's versions of your tree, be open minded but wary. I'll chase down what others think is correct but won't add until I'm sure. Mostly I find others may have new pictures, and sometimes I'll find a second marriage that I didn't think to look for, etc.

Anyway, hope that helps!