Making older homes more energy efficient

Hello. We’re in the process of rehabbing some older homes and trying to find some innovative ideas on making homes more efficient for new tenants at an affordable price. So far I’m considering interior storm windows and insulation that wraps around skirting. Anyone have any other ideas?

Insulation insulation insulation (under belly and roof, specifically). LEDs. A couple states we work with have great westernization programs for the homes where a large portion of the cost is covered.

@westewart Has it right. We too used a State program for 0% interest loan in new windows for a couple of our POH rentals. Here are a couple other things to look at.

Exterior door seals and jams
Light switch and outlet insulated covers
Extra sealant on any side of the home that gets a lot of cold directional wind
Old trailers have old appliances- refrigerators, washers and dryers… $$$
Dryer vents and piping clear and clean

Looking into house wrap and insulated vinyl siding. R-11. Would also bring up the look of the property. Has anyone tried this?