Such a great question. I've struggled with this, too.
I like Angie's short answer because it's realistic if you're really adding something quite different.
Once I finally realized what some of those changes entail, I was able to start evaluating the "cost" of making certain changes. Not, don't make any, but be smarter about it. Of course, "love" isn't always smart, but, "informed love" is possible!
For example, I knew I just loved oxfords. So it was worth it to me to figure out what I would need to wear to work them in. That meant I added some clothing that was oxford-fashion friendly according to fashion mags and blogs, and it also meant that I discovered that I don't like "me" in some of the fashion-world oxford outfits either, so I didn't try to add there, and it meant considering wearing them in ways not everyone else would as long as it looked good to me.
A related example is different loafers and low-vamped flats. I'm also drawn to those, and can get some good foot comfort, but they look best with narrow-hemmed pants or ankle pants, and I had had more wide-leg pants. Tapered pants, on me, are tricky--the right cut and it's very flattering, and wrong, and oh boy. Also, ankle pants can chop up my proportions and be too chilly even in summer, in air-conditioning! So here I focused more on full-length narrower pants that "scrunch" and a few selected ankle pants for summer so I could wear loafers more of the time. I continue to wear the longer, slightly scrunched lengths because I like them and they're wearable for more of the year, even though perhaps that is not trending.
Another example is the trend, when it was a newer trend, toward fluid and even oversized tops. This was a good direction for me, if not too exaggerated and bulky, because I don't like very fitted tops and because these work well to "sportify" pencil skirts, to look more relaxed and less corporate, and pencil skirts worn not too long work for me with flats (yes, I know, some say pencil skirts should only be work with pumps!). So this was a trend that worked to my advantage and with other pieces I already had.
Then, the longer pencil and tube skirts and midi skirts are something I like because of a ladylike vibe, but for me they are challenging for footwear. Yes, I see them shown with oxfords and loafers on models, and especially tall slim gals, but on me I find the proportions and legline depressing, so that's not my look. So if I add a longer skirt, I have to think very carefully about where and how I'll wear it as most of my footwear does not work with them, for everyday wear ( I can wear more heel for special occasions). It might be confined to a small capsule where just the right skirt works with one pair of shoes and a few tops and I don't try to push for a large expansion there.