Basements

One method to insulate your basement walls is to use styrofoam sheets. They come in various thicknesses from 1/2 inch up to several inches.
The sheets can be cut with a knife to fit any space. If you have stud walls, cut the sheets to fit between the studs and glue them to the concrete wall with construction adhesive.
Styrofoam sheets are also an effective sound barrier. You can use them to insulate the walls in bathrooms, laundry rooms, and furnace rooms, so you can enjoy your basement den in peace and quiet.

Insect repellent

Before you insulate your walls, sprinkle a little borax (like 20 Mule Team) in the wall cavities to help repel insects. It also works to sprinkle it around the garage, in cabinets, and in small openings around the exterior walls. It doesn´t kill them, but they don´t like being around it and will leave the area.

Save money

You can save money on your utility bills by insulating your attic.
Batts are made of fiberglass (which can make you itch). They come unfaced -without paper; faced -with paper on one side; or in an envelope which protects you from the itch. You can lay the batts either between the ceiling joists, or across them.
The idea behind insulation is to create a dead air space. The insulation should be fluffy, not packed down.
Blown-in insulation comes in compressed bales which are opened into a blower. The blower is basically a fan which moves the insulation through a long hose. You aim the hose throughout the attic and blow as much insulation as you want. The deeper the insulation, the more money you save on utilities.

Whichever method you choose, BE CAREFUL. Do not step on the ceiling. Walk on top of the joists. It may be easier to take a couple of boards to the attic to stand on.