As Otto says, but also take time to clean and true up the face of the inlet or no gasket is going to develop a seal….
Just adding a gasket or crush washer may keep the fitting from bottoming out which will go a long way to not leaking…
I would start with a gasket and Teflon tape on the threads, if that leaks then I would go with the seal lock type products …
I’m a methodical person… try simple first……. then get more extreme…
Chuck
