Saving money and saving the environment often go hand in hand.
For example, consider how much of a product you use. I've seen people on here mention that they use what seems to me like alarmingly high amounts of toiletries, cleaning products and 'sundries' like cling film, toilet paper and kitchen roll.
For example, a whole bottle of shower gel per person per week, bleaching everything in sight daily, the memorable thread where a poster was spending £30 a month on kitchen roll because she used great handfuls of it daily. Daily bleaching simply isn't necessary, most of the shower gel from a great big squirt will just go uselessly down the drain, etc.
Comparitively, we use hardly any of these things, with no noticeable loss in lifestyle, cleanliness etc. Shower gels tend to last a few weeks, we only use a few bottles of bleach a year, we're not deliberately restrictive with cling film and foil, but we've been using the same roll of foil that we brought back from holiday nearly 2 years ago (bought it to wrap up some leftover pizza to take on a day out) and the roll of cling film we have is older than that.
The cost of these items might seem small, but all those shower gels, bleach etc come in plastic bottles and take great big factories using lots of chemicals, water and energy to produce. Reduce the amount you use and you reduce the amount of plastic bottles for a start.
Also cut open tubes of cream etc to get the last bits out. If the face cream I use comes in a squeezy tube, I squeeze it out into a travel container anyway because I find it easier to use and use the right amount that way, but when it is starting to get hard to squeeze the cream out, I cut the tube open and scrape out the remaining amount, at least 10-20% of the product remains in there, so by doing this, over time, you reduce the amount you buy by this amount.
I also bought long 'sundae' spoons from the pound shop, so I could get the last bit of peanut butter out of the jar easily, because again, about 10% of the peanut butter gets stuck in the curvy bit of the jar, which I found annoyingly wasteful, on both a money and an environmental level.
Also look at the Moneysavingexpert money makeover, for a systematic review and comprehensive list of tips. You should always be on a deal for your gas and electric, broadband etc, and you should always shop around and look for a discount code before buying anything.
For food shopping, either shop in Lidl or Aldi for as much as possible, or if that doesn't suit you, make sure you only buy on special offer for any non perishables that you buy regularly. It makes no sense whatsoever to buy one of an item each week, when you can buy a four pack every four weeks for much less, eg Heinz tomato soup at Tesco is 95 pence a tin, but 4 for £2.50 and if you do this for as many items as possible that you buy, the savings really add up. There is simply no need to pay 'full price' for a whole range of items like pet food, canned goods, toiletries, cleaning products and many other items, because they're always on offer somewhere, so you only buy them at this time, and buy enough to get you through to the next offer.