I do a lot of traveling. Not necessarily because my family is heavy on the vacationing, but mostly because all my extended family lives 8+ hours away, yet we like to pretend we're close enough to visit as often as possible. This means that, especially in the summer, I'm constantly getting surprised with spontaneous visits to the see the fam.
Over the years, I've worked out a pretty foolproof system of packing that allows me to get it done in about 15 minutes.
Step 1: Divide your packing into three categories
For me, this would be clothes, toiletries, and additive items. Breaking your packing down into smaller sections makes it easier to attack, and working through one section at a time means you're much less likely to forget anything.
Step 2: Clothes
I start by mapping out my entire trip day-by-day, noting what sort of outfit I'll need each day. (e.g. casual, dressy, comfortable, classy, etc.) I roll my clothes to save space and prevent wrinkles. Stuff your socks into your shoes if you're worried about unpacking misshapen footwear!
Step 3: Toiletries
For these I have a couple different travel pouches. I fill up everything I need into their appropriate pouch, and then I leave them on my dresser to be packed in my suitcase the next morning after I've gotten through my morning routine (which usually requires some of the products I would have otherwise packed away.)
Step 4: Additive Items
This is sort of the miscellaneous section. Usually this is anything I need to keep me entertained in the car, any schoolwork I need to get done in my downtime, or any random amenities like food or water bottles. This section varies from trip to trip, so there isn't much of a system to it other than throw it in the bag.
Step 5: Make a "morning of" list
There are always a couple items you can't set aside until you're about to head out the door. To ensure you don't forget anything, make a list to check off the day of your departure. Usually this includes things like my contact case, my retainer, my charger, the book I'm reading-- things like that. If I don't want to pack it away in a toiletry bag or my suitcase ahead of time, it goes on the list.
And that concludes my five-step routine to packing! I'm a big fan of routines, so talking about the ins and outs of packing processes is always a good time for me.