I think you should only set up a simple elementary approach using the FIX page and LEGS page (if you must do that). Do all the rest on Heading Mode and flying the aeroplane using the autopilot in Heading and using radio inputs rather than going head down for 5 minutes setting up procedure turns/altitudes/speeds and trying to fly a procedure in LNav. FMS is not a new way of doing things, just an enhancement and aid in your current way of flying. It is still not to be implicitly trusted and relied on.