Lovely goal! The risk of our hobby (in particular for those amongst us who have played for more than a few years and more than a few games) is that we end up with a huuuuge backlog.
The missus and me made an agreement quite a while ago: I own a large closet and a display cabinet. The total amount of miniatures can never exceed the space of said storage. Furthermore, the amount of unpainted miniatures cannot ever exceed the amount I had at one point when we made this agreement. This means that I have to finish or give away a regiment / mini before buying something new.
This agreement has worked quite well. The storage limitation has promted me to come with more ingenious storage options from time to time, but as it;s now I can keep armies stored well enough. (it’s two armies over over 10,000 points each and a handfull of smaller armies/other games). Eventually, I may have to sell/give away an army or two but when that’s the case, I have an army lined up that I don’t use anymore.
The painting limitation (first finish something, they buy something new) really prevents me from impulse-buying or kickstarting minis and also encourages me to finish started projects. Currently, I’m at 22 minis “room” for puchase. So I can buy a new regiment if it comes to fancy, but no more frenziend scrounging ebay unless I get rid or finish of the ebay puchase I made a year back.