Use A/C and central heat less. Turn on fans or put on a sweater.
Shop sales only, for gift giving. You'd be amazed how much money you can save.
Before buying the 'economy' size of something, do the math and see if it's really a bargain. Many times, that 'economy' size costs as much or more than the same quantity, from several of the smaller sized containers.
Buy store brands, IF the quality is just as good.
Sometime it is, sometimes it isn't. In my experience, store brand shampoo is often watered down, causing you to use more. There are inexpensive brands, like Suave, that are good (Suave was even recommended by my hairstylist).
Some store brand foods are made with lower quality ingredients (ran into this, with cake mixes). Just compare labels, to make sure the ingredients are the same.
Most store brand or generic drugs are the same as name brands, so you can save a bundle there.