Learn Regex the Easy Way
My biggest issue with regular expressions is remembering the exact syntax of each of the different common regex engines. Javascript, Perl, `grep`, `grep -E`, vim, `awk`, `sed`, etc...Each one seems to have slightly different syntax, require different characters to be escaped, has different defaults (is global search enabled by default? Multiline? What about case sensitivity?), some don't support certain lookarounds, how does grouping work, and so on.