I think I found a better way to level up Advanced Tech than repeatedly cleaning holo pets. While cleaning holo pet is alright, it requires way too many click and since you have to click on the sprite to queue up actions, it gets more painful.
Better (in my opinion) and faster way: Power Cleanse.
Power cleanse seems to level quite a bit faster than Quick cleanse, even faster than cleaning holopet, and it raises skill the entire time you are showering means less click and also easier to queue up actions.
The drawback is you cannot do power cleanse until upgrading the sonic shower at L9, but if you already have one upgraded (by another sim) you can do this from the beginning and it raises skill FAST!
This is easily done because Plumbots have innate hidden L10 Advanced Tech, you only need to equip them with limitless learning to enable the "upgrade" option.
To maximize your skill gain, make sure to start dreaming for Advanced tech as soon as you can, it would double the speed for 12 hours (I think you can do this at L2)