Personally, I mentally recite the mantra "wallet, phone, keys" about a dozen times a day, while tapping the relevant pocket - it's not really a hack, but it's pretty effective. The nice thing is that, after a few repetitions, the mantra becomes this single block that you recall in it's entirety, rather than a list of items to be remembered individually. Combined with the tapping, you learn to recognise both patterns, and if you miss an item in either then the two become jarringly misaligned.
You can make the mantra as complex as you need it to be, with a dozen items if necessary, and you still only have one "thing" that you actually need to remember. With repetition, "wallet, phone, keys, pen, watch, hob, window, lights" is no harder to remember than "wallet".
Spend a week or two making a conscious effort to perform this recitation/tapping ritual in any place where you might previously have lost something. Hopefully, by then, it will be something that you do instinctively.