I started with a an 2nd hand Chinese ebay CNC .. I've learned a lot and tbh I have enjoyed the learning, its frustrating sometimes ..but when u get it right (finally) it a great feeling.

Some basic mistakes I made ..

Set a budget
Bought a machine the size of the work that I was going to do.. shouldn't of done that. Now I want a bigger one.
Budget at least 25% or £400 for all the peripherals u are going to need.. clamps, water pumps + anti algae liquid + bucket , dust extractor.. stool so you can sit there staring at your masterpiece being created """Dust-Boot/Shoe"""" so you dont have to sit there and stare all day ..lol ear muffs glasses computer - monitor - keyboard -mouse operating system..
Software.. most don't have controller software check first by email, and make sure its a legit full copy not a trial.. or that's another £150, the design software ..ArtCam etc expensive.
And tips
Learn how to set your work area extents and test them ..
Do not put a bit in the spindle until you have dry run all your g-code several times or risk plunging through the bed in the first pass.
Put all your spindle spanners on long chains or paint them bright fooking orange .. :)

Hope this is of some help.