The priorities for reducing heating costs/more comfortable house are:
* attic insulation
* insulated windows
* professionally installed, insulated doors.
Attic insulation is an easy DIY. Could cost $200-$500 for fiberglass with a payback of 2-5 years. And much more comfort in winter and summer. You could ask the landlord to pay for the insulation, and you install it. If he won't, just do above the br and baths that you use.
For a rental, I would suggest door and window insulating strips (draft blockers) plus plastic on the windows. Here, we have blocked off one of 4 exterior doors to reduce drafts.
I would reduce any drafts into the basement first, and not insulate under the first floor unless there was a crawl space. With ins under the floor, there is difficulty in keeping it close enough to be useful. Professional spray in foam insulation ($$$$) could be used. For a basement, you would worry about freezing the plumbing.
If you ask around at local thrift shops/freecycle, you may be able to get FREE or really cheap wool rugs for the floors.
It sounds like you have
radiator heating. Have you tried insulating the hot water pipes in the basement? Also, vacuum the outside of the radiators to improve the radiation of heat.
You might want to look into this product:
http://www.radiantguard.com/index.as...PROD&ProdID=37
reflective bubble insulation. It is available at Lowes, Home Depot, etc. And portable, so you can take it to the next house. I would suggest trying it above one bedroom, to see if it makes any difference.
Also, if you bring in a furnace service technician (about $100 here) it is possible the technician will find something wrong with the boiler. Get a written report, and make the landlord pay to repair of replace.
My sympathy to you for having such a cold house!