I thought I would have trouble with my husband's Wilson ancestors, but in fact, by following the usual principles of working back from what you know, I have got there.
All I knew was his grandmother's name Mary Cowan Wilson who married a Fleming. From her marriage certificate I got her parents' names William Wilson, carter and Isabella Mcfedries. I found them in a census in Tarbolton. On his marriage certificate to Isabella he is 42 in 1872 so he was born in Lanark about 1830. From the marriage certificate I got his parents - Henry Wilson corn miller and Janet Ewart. But I still couldn't find his birth.
Since 1830 is before statutory recording, it is possible there is no record. You can search the International Genealogical Index for free, good for up til 1875. Old Parish records can be searched for free on Scotlandspeople but you need to pay to see the results!
I found Henry Wilson and son William both at Cambuskeith Mill on the river Irvine outside Kilmarnock in the 1861 census.
I got stuck at this point for a while. A good piece of advice I got when I was starting out is to publish your tree on several sites and I now have 3 online trees. I put what I knew on the Ancestry site and a gentleman in Australia got in touch. It seems that shortly after 1861 Henry and his second wife went to Australia. From Australian certificates it turns out the mother's surname was Jean Dewar not Janet Ewart! William's marriage to Isabella was his second, she was much younger, and he lied about his age. Or maybe he truly didn't know how old he was and presumably he had only heard his mother's name. He was actually born in 1822. The morals of the tale are keep your search wide and don't believe everything you read on certificates!
Cambuskeith Cottage (pictured) is up for sale. The mill ruins are in the garden.
Link to Henry Wilson on my tree