I think starting with a closet clean-out makes the most sense. Start by tossing out anything that is frayed or too worn. If it is a much-beloved item that you reached for time and time again, then take a picture of it and make a note to upgrade/replace. These items became much-beloved for a reason, and they are clues to your style.
Toss out (donate) anything that doesn't fit. No saving items because you may gain or lose weight. Out it goes.
Donate anything that simply doesn't flatter. You know which ones these are: they are the ones that have seen little wear and you can't quite put your finger on why that is. Maybe the color is all wrong for you. Out.
Next make a pile of everything that still fits and flatters, but is out of date. If you've owned it longer than 10 years, it's probably out of date. But that's not always true. Some items like pencil skirts are classic.
So take a look at these items and ask yourself if tailoring is 1) possible 2) worth the effort and expense. It might be for super-classic items, like a pencil skirt or a wrap dress. One quick, frugal and easy way to refashion items is to simply take up the hem to knee length. You may be able to save coats, skirts, dresses, and capris this way. And skirts in particular are very easy to have tailored down for a shrinking body.
Do you have a lot of button down woven shirts? Try them on and see how they fit. If they are still in good condition, consider whether simply taking in the waist with a few darts would help revive them and make them fit better and look more modern. Maybe you wore these for your job but you can refashion them to wear in a MOTG outfit too.
A lot of the difference between a classic piece that's 10 years old or older, and a classic piece today, is in the fit. The modern fit tends to be more form-fitting. Take jean jackets for instance. The classic of 10 years ago was looser fitting all over. If you have one that fits in the shoulders, but is loose elsewhere, you may be able to have the waist taken in to modernize it.
Next, take whatever is left over, and lay it out on your bed. Then PLAY. Mix and match items and see what you can come up with, following the MOTG rules and smart-casual rules. Get creative and think outside the box. You may be very surprised what you can come up with! You can also post the items here, and we can give you ideas as well.
When I first started YLF I did this and it really opened my mind up to the possibilities of what was already hanging in my closet. Even today (over a year later) I will see someone post a pic of an outfit combo and it'll make me say, "Oh! I have a shirt like that and I never thought to wear it quite that way!" We tend to get stuck in ruts wearing the same uniforms over and over and wearing one piece in only one way. For example you may think a silky dressy blouse only goes with dress pants for work, but it can be repurposed numerous ways - including with jeans for a smart-casual outfit.
In some cases, you may find an outfit combo that works but you are just short of one key accessory or piece, so make a list of these items. I keep my list on a spreadsheet, and then when I go online shopping I cut & paste the URLs into it.
When you do all this, you will begin to notice where the gaps are in your wardrobe. Maybe it's tops. That was the case for me. I had numerous basic GAP scoop and V-neck tees, and plain solid scoop and v-neck sweaters, but not much else in the way of tops. So I made that a big priority at first, and focused on collecting cardigans and better quality knitwear and silky blouses with interesting details.
Or maybe it's shoes. As MOTG, shoes are important and you need shoes to match your lifestyle. Lots of us dress for our day starting with the shoes: lots of walking, we need comfy flats.
Anyway, you will begin to see where you need to start. It's probably not "everywhere." There are likely some things in your closet right now that can be repurposed/refashioned/tailored etc and can be the basis you work from.
