I have also learned to be cautious. I must say that I do not much like the big Genealogy sites whose view of reliable sources is no greater than quoting their own customers' unsourced trees. 

"Collectors" can really be a nuisance, like the lady a year or two back who approached me and asked for some help with her tree because she had been "doing" her genealogy for nearly a year and had only found 26,000 ancestors! She did not know what I meant when I asked if she had sourced any of them.
A little information first and see then what develops.  Sometimes one can find a most useful and reciprocal partner and that can be great. It's fun to help but care is the byword.
Martyn Woolf
London