Straight male here
I've always thought the Prince tennis skirts looked very good... for example the Tour line:
I think they fit very well on the, uhh... backside

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I'm not really the best one to offer advice

When I'm watching tennis, I'm not looking for girls to be all glamorous and dressed up, or all slutty and dressed down... I want something athletic. Simple. Something that says- I'm here to play tennis. There's something sexy about that
Best advice I have- keep it simple. The ones who think they are awesome always come out with their 3 wristbands, matching outfit with matching visor, most expensive stuff they can buy... and as soon as I see player like that I know they're pathetic

It's more intimidating to be simple