When I met my husband I was 34, 5'4" size 12 (5 years ago), so why don't I tell you what I wore the first few times we met:
Met for first time ( at local chamber of commerce event)
Black shift dress, lacy knit shawl in lieu of cardigan (in was snowing), black knee high boots with kitten heel, cross body bag made of recycled ring pulls
First non-date total pretext of my doing work meeting
Navy shift dress with navy ballet wrap cardigan, grey flat over the knee suede boots
Second non-date another total pretext of his doing lunch
Big grey Tweed overcoat, big russian fake fur hat, same lbd as original meeting underneath with grey flat over the knee suede boots this time
First proper date
Grey marl merino sweater with 3/4 sleeves and boat neck, slouchy a-line mini in grey raw silk with a silver, grey and gold jackson pollock style splashy print on it, grey boots again
So I would say
*you need to feel relaxed and yourself
*something classically feminine works
*have one sexy feature on display (legs or bum or cleavage, not all three and probably not cleavage at this point- but something tight-ish that defines the outline of your bust, definitely)
*display a feminine silhouette in whatever you choose but not too much skin (e.g. shift dress or skinny jeans or mid-thigh mini skirt- whichever is more your style, but make sure you define your waist)
*heels never hurt, don't have to be skyscrapers though
*long boots are good too, but flat-ish if they are over the knee
*nice perfume, not too much make up
Don't try to monopolise him, but when you are speaking to him, turn on the charm full beam.
BTW, I was totally skint at the time, as I had just paid for my mum's funeral so I was in a mix of hand me downs from friends, charity shop finds and sale bargains most of time. I was dressing much less trendily/cooly than I usually did as a result. Think this made me more approachable. My point being, as long as you don't look like a scarecrow and present a silhouette that makes him realise you are of the opposite sex to him, if it's meant to be, and the chemistry is there, it will happen.
Good luck.