You asked about the research methods I use:
1) a strong degree of scepticism in relation to other people’s assertions.
2) Ancestry, in particular the “related/suggested records”, accessed using the small left-pointing arrow on eg an image of a census page --- you might discover something you hadn’t thought of searching for. Also, it gives quick access to other census pages; this is particularly useful if the names have been mistranscribed and you hadn’t been able to find them. (Be careful to weed out the records which aren’t relevant to your search).
3) Ancestry “search – Public Member Trees”. Ignore any which are clearly just cobbled-together chunks from other trees--- these usually have a large number of “people in tree”. For any given tree, I usually go straight to “tree search--home person—tools--view in tree” to discover whether the “home person” (usually the tree compiler) is a direct descendant of the line you’re researching.
5) Brian Lawson’s IOM census index---a brilliant tool, and generally very accurate (with a low percentage of errors). Getting the best out of it takes some practice and experience, but worth persevering.
6) IOMFHS---if you’re not a member already, I’d definitely join. Then you have access to burial index and wills index. Use the burial index alongside familysearch deaths so you can view burial register images which sometimes give clues.
8) for records later in the 19th C and the 20th C, www.manxbmd.com
9) Frances’s Manx Note Book, accessed via the green “local” at the top of this page.