I have thick wavy dark auburn hair that hides imperfect cuts pretty well, so I occasionally trim the overlong bangs or side layers a bit, if the mood strikes me. However, I'd never attempt a whole-head trim as I have bad peripheral vision and would certainly screw it up. Coloring is not as bad---I colored my hair for years when I just need some minor grey coverage---but real cutting (i.e all over my head) to me is fraught with perils. I wear my hair in long layers that can go 4 months or so without a trim, and have cultivated a longtime stylist at a local, inexpensive "quick cuts" type salon. I found her through sheer luck--walked in one day for a bang trim and because she had the same hair as me (and hers looked fabulous) I let her give me long layers. She does just what I want (quick trim of bangs and layers) and charges $25 plus a tip. I'm S.O.L. when she decides to retire....she's down to just 3 days a week and I keep begging her not to go!
For color, I've done it all different ways but have finally settled on a way that works. I used to do my roots myself with a box color (messy and not always the best coverage but it worked in my 20s and 30s to hide the occasional grey hairs,) When I was just covering a little bit of grey, I could get by with doing myself every 3 months or so. Once in a while I would screw up and go too light or too dark and had to have a professional fix it but that only happened maybe twice in 20 years of box color. However, when I hit 42 or 43 (can't recall exactly...) I faced the fact that I had gone past covering a few greys. I was about 50% grey and had obvious roots that NEEDED covering every 4 weeks. I bounced around from salon to salon for a few years but hated paying the high prices for a retouch.
When I got married at 45, I decided to make a big change for my big day. I went slightly crazy (for me--I am frugal) and had a makeover at an upscale salon, including great cut, a whole head highlight and new color. I was a strawberry blonde with highlights for my wedding and loved it. However after the wedding hoopla. that look was just too high maintenance and I decided to go back to brunette with monthly retouches for the grey. This time I went to my local cosmetology school and asked the head instructor to take me back to a natural auburn brown. I was worried about having a student work on me but for that first time, they actually used me up on the school teaching podium for a class in 'going back to natural color' and the head teacher did the color formula and application and it turned out great. The students have been doing my retouches ever since (3 years). No problems as long as they follow the teacher's formula and she checks their work before I go and doesn't let me leave until it's perfect. For $25 and tip this is a bargain and I feel pampered because the students are always happy to see me and take their time.
My solutions might not work for people with more fussy hair but these methods have worked better for me than trying to learn new skills (cutting and color) myself.