For the wardrobes, throw everything out of the wardrobe onto the bed ( or the floor if there isn't a bed. The main thing is to get everything out ).
Take three large rubbish bags. One is for actual rubbish, one for donations, one for things you might actually wear .
Buy a large number of clothes hangers .
Put your favorite music on.
Go through each item, and make a decision. Either throw it out into the rubbish bag, donate it, or put it into the "wear" bag.
Once you have done that, put the rubbish bag outside to be thrown, put the donate bag into the car to be taken away, and put all the "wear" clothes in a corner.
Get some cleaning products and cloths, give the wardrobe a good clean . Vacuum the floor. Spray some nice fragrance around. Leave it for a couple of hours to dry .
Decide on what is going on every shelf and stick to it . Things like knits, handbags, etc need their own shelf.
Anything that can be hung up, put it on a hanger and put the clothes in according to colour , or tops / bottoms , or according to the person if there is more than one .
For rooms, it's much the same. Divide the room into parts if it's all too overwhelming . Same process with the rubbish bags - one for rubbish, one for donations, one to keep. Be ruthless - don't hang on to things "just in case". Add a box or bag for " things that don't live here".
Play the music, pick each thing up once and make a decision. Don't dither / waste time thinking about it. You know if something is rubbish, if it's got some life and can be donated, if it's useful and you need to keep it. If you are keeping it, put it in a keep pile.
When you've finished sorting, get rid of the bags. Clean the area, let everything dry. Put all the "keep" things into an appropriate place.
If you do this once a year, it will never accumulate and overwhelm you. Make a date to do it, allow a day , and get it done. Good luck !