Here's one that might be good for the noobs.
You've maybe read about this lovely stuff called PBW (powdered brewery wash); relatively cheap, and advertised as great for cleaning your equipment. You may have looked at the price and thought, oh heck no, I can do just as well with storebought oxyclean (scent free please) and other household cleaners. (Never bleach, please and thank you.). I'll be fine!!!
Then, after nine years of homebrewing, you finally decide to buy a 1lb tub of the stuff, just to see what it can do. Leave it on the shelf for a few weeks, because busy. Then one Saturday, that you finally have free, decide to use it to clean some somewhat nasty kegs that you've had for several years. Always rinsed out, scrubbed a bit at the crud inside, but thought oh heck this is fine. That Saturday, you fill a keg with hot water and the prescribed amount of PBW, thinking well, it might do some good. Leave it in for 30 minutes, shaking several times. Then....
You dump it out (or push to the next keg needing cleaning). Pop that keg lid and...you are temporarily blinded by the shininess inside. Without any scrubbing, that stuff did away with several years of scale/beerstone/nastiness. Leaving a keg that looks brand new on the inside. And you put on your old softball cleats, and proceed to kick yourself into next week for not doing this sooner.
I made up ONE 5g batch in hot water, and it proceeded to clean three kegs to a fare-thee-well with minimal scrubbing. Right now it's recirculating through my plate chiller to give that a good cleanout. All for less than $3 per treatment.
Why didn't I do this sooner? Good question. Thought I could do things cheaper, or my cleaning was sufficient.
TL;DR; PBW is your friend. You know, that friend that comes over on a weekend and helps you clean when your in-laws are coming over, and doesn't expect anything in return. DO DO THAT.