Advice on Paying Social Security for Hired Help?

[WriterinExile]

For those of you who have hired contractors, plumbers, painters, electricians, etc., what has been your experience in paying not only their wages but also their social security? I have been cautioned that one can get in trouble by not paying it, with the implication that paying it is a hassle (ergo, better to hire an architect to oversee everything and take care of such business details). I'd love to hear your experiences and advice. Many thanks!