You can make a fake license plate. You can make a fake face. In both cases, it only needs to 1. not look out of place at a glance, and 2. hold up for just long enough to do the crime.

For the license plate, 3D printing + a 30-second paint job would work just fine. Make it an out-of-state plate. Don’t make up a number; read a plate off of one of those public surveillance-cam live feeds of highway traffic from a different state.

If you’re going to do something really bad, it’d be better to steal a car and put the fake license plate on it; commit your crime; drive this stolen car to, and leave it in, the airport long-term parking lot, and then strip off your disguise in the airport bathroom and take a cab home. (That way, they’ll think “the suspect” fled the city/country.) You could also bring a hand-vacuum with you, use it to detail the car, and then pour bleach all over the car’s interior once it’s clean, to erase both your epithelials, any other epithelials, and to contaminate any blood evidence. Bring the vacuum home with you; empty the filter into a garbage can at least a few streets away; then wash and bleach inside it, too. (It’d be better if you could get a bagged hand-vacuum, but I don’t know of any.)

For the face, skip the silly Halloween masks and go with Hollywood-makeup-dept facial prosthetics, e.g. put on a beard; put on a skin cap to make yourself partially balding, or on top of it, add a short real-hair wig, such that your regular longer hair would have been impossible to grow out in the intervening time; wear fashion glasses if you don’t need glasses, or wear contacts if you always wear glasses; and any other things you can think to do that will change your BOLO description in ways that they don’t expect to be easily changeable (e.g. increase your height by a few inches with subtle platform flats!) Then, use some silicone pads + foundation to add some volume to your cheekbones/forehead/whatever, such that facial metrics computed from imagery of your crime won’t return a match to photos of your normal face. Buy all of these things in different cities than the one you live in, paying cash, using a lesser disguise, at least six months before you intend to commit the crime. (In fact, buy them as an “in case of emergency, new identity” kit for yourself long before you ever decide to commit a specific crime.)

Oh, and of course, whatever you do, wear gloves and shoes. Specifically, new gloves and new shoes of a different make and size to your regular ones, both purchased at least six months in advance. Afterward, burn/melt down your whole disguise kit (gloves+shoes+prosthetics) and throw the remains of it away away in a different city. If you plan to use a gun, use tough gloves, such that slide-bite won’t pull your DNA. (Of course, discard the gun. Disassemble and melt the components first in a DIY sand-box crucible using a blowtorch; then throw the slag in a body of water. The most important thing to melt is the inside of the barrel, to destroy rifling characteristics.)

And never touch any part of your skin to anything during the crime. For example, don’t bite anybody. What are you, crazy?

Finally, maybe consider committing the crime in a different city/state/country than the one you live in, if you can: commute in, do it, commute out. That’s rarely an option for most crimes, given that your “target” is probably someone or something you know, that lives in your city. But, if you’re sufficiently dedicated to doing this, you could move out of your city months in advance as part of the plan, just to return on that one day, commuting in under disguise while you have an alibi back at home. (I’d suggest a remote-work job, and a script to realistically automate the doing of a day’s worth of that remote work, including driving a headless-browser for goofing-off time.)

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Source: mostly a lot of studying forensic case-files and asking myself what I’d do differently. It’s a fun way to pass the time when you have to read this stuff anyway for work.

I don’t really feel unethical giving any of this “advice”, because real criminals will never follow it, as criminality is strongly linked to a lack of impulse control. Nobody ever really plans [non-white-collar] crimes months in advance; or if they do, they don’t seek out resources to help them plan, thinking their own naive plan is bulletproof. (Or, on the other side of the spectrum, they feel in need of “authoritative” advice, so they buy books about the crimes they’re going to commit and keep them in their house; rather than, say, finding a text on LibGen through Tor and keeping it on an encrypted USB-key that they look at only through TAILS.) People with high-enough IQs, detail-oriented-ness, and problem-solving abilities to get away with crime, have better things to do with their lives than committing crime†.

(Consider, by analogy: nobody would ever catch you running a meth lab, if you actually followed proper chemistry safety and disposal procedures, something any YouTube chemistry-video creator can manage in their own home just fine. But what criminal chemist does this, even with a strong monetary incentive to do so?)

† Or they become mob bosses.