This is a perfectly office-appropriate outfit. If your office is chilly, you could always layer a long sleeve top underneath the dress, or toss a cardigan over it. The tights are a fun way to be a little bit trendy and the accessories add a little punch of personality and style without being too over-the-top. If the lace tights are not warm enough for you in these cold winter months, then simply layer them over a pair of opaque tights. If you want to be really crazy, layer them over a pair of bright jewel-tone tights. And yes, it's perfectly fine to wear a brown dress with black tights and shoes- the rule about not mixing black and brown (and navy) is actually very dated. Since black, brown and navy are all considered "neutrals" that means they go with everything-including each other!
Let me know what you think of my collage outfit and if you'd like to see more like it. If you have an outfit conundrum-maybe a piece you love but you aren't sure how to style it, email me a picture of the piece, along with a brief explanation of where you'd like to wear it and what you're having trouble with. I'll create a collage (or 2 or 3) to solve your style dilemma.