Speaker positioning is one of, if not the most, overlooked things that can make a very noticeable improvement and it is basically free. Just your time and listening.
"Free" room treatments can also make a big difference, especially in a "Live" room, where there are more hard surfaces than soft/dampening. A soft rug in front of the listening position if you have hardwood floors, curtains vs. hard blinds, etc... Not entirely free, but can make a difference in the way the room sounds...and maybe add some WAF too if you let her pick it out. WAF goes a long way to improving your listening experience.