I shifted from mostly wearing tshirts to mostly wearing tailored shirts and blouses (if mostly unironed ones) a couple of years ago. Partly because they look nicer/fit my current shape better, and partly because they do seem to get me taken more seriously at work than the geeky tshirts. Or maybe the external change happened at the same time as me getting/projecting more confidence, and confidence is helped by feeling I look good, so it could be a bit circular, but anyway it's working for me.

Of course, I don't actually like ironing any more than I used to, so about half my shirts sit unworn for weeks on end as they really don't look good unironed. I'm vaguely trying to find someone to pay to iron them for me once a week or fortnight, but no success so far.