Many of us have old homes. Mine is a 220 year old center chimney colonial in New Hampshire. The First area that you need to attack is 'air infiltration'. Most of your home loses its heat through the top(attic). So first step is to get into the attack and seal any and all penetrations from the living space to the attic(cold space). These include wiring, vent stack, bathroom vent, partition top plates if you have them, lighting fixture boxes etc. Seal any larger holes with expanding foam and smaller holes with quality silicone chaulking. After and only after all of your holes are sealed up so that heated air doesn't literally fly right out of your house you need to slow down the heat migrating from an area of warmth(house) to the area of cold(outside). You need to do this by properly insulating your attic. That means that in old homes where the ceiling joists aren't equally spaced you need to use a insulating product that will completely and tightly fill the voids. The best product for this is blown cellulose. Personally I did not want to lose the ability to get into my attic to do work so I filled the joist bays to the top(8 inches of blown cellulose which is about R24) then I rolled R30 fiberglass insulation over the whole attic butted up nice and tight to each other. This allows me to peel back the fiberglass and get to where ever I need to work if that is the case. This gave me an R54 which is under the suggested R60 now in my climate but helped immensely. If you can find a way to insulate the rim joists in your home it will help but the biggest thing you need to do is plug and holes or spots where air is freely being pulled inside the house from the outside around the rim joist. Chaulking and expanding foam work well in this area. I have 8x8 sill beams which means I have about R8 for insulation already at my rim joist, I just sealed any leaks. Lastly walls are the place to go. In old homes they can be very tricky because you need to keep moisture out of the wall by air sealing them when you insulate. If you have any interest in that let me know. I have gotten a pretty good method down for doing that which seems to work very well.