Hi! I use this codeto generate (“, tags”) ctags file.
map <Leader>tags :!ctags -R --languages= .<LEFT><LEFT>
After every saved if exists a tags file I update tags with last modified.
autocmd BufWritePost * if filereadable('tags') | exec ':silent ! ctags -a %' | endif
If tags file exists I load it in my session of work
if filereadable("./tags")
set tags+=./tags
endif