Hindu wedding-wise, the only real no-no would be all-white, top to toe, on any woman (it's the widow's hue, so unless you actually are one...) --- but that's also to do with how traditionally inclined the family and/or friends are. I know I searched high and low for a white wedding saree myself, and was rather sad not to have found one though family members were most relieved
Black is generally avoided too, though --- it's considered a joyless, luckless, non-colour and hence weird on an auspicious occasion, more so for women than men (who sometimes will wear their nice black suit anyway).
Red is often the bridal hue, but this varies for some communities and many don't adhere to that as strictly any more. However, unlike in a church wedding, you can happily wear red too --- in fact, the more the merrier --- without feeling you might upstage the bride.
Another thing to keep in mind: The most pared-down ceremonies are typically waaay longer than the average church ceremony, no matter how elaborate. Keep your heels comfy for standing as well as dancing, and your skirts/dress easy to sit down as well as shake a leg in! (That's one more reason to consider bringing a friend, though there are often group dances more than pairs at most Hindu celebrations.) Helps if your clutch has a strap as well, for the more 'energetic' dances. And there's often flower petals shedding all over the place, so shoes that won't skid too easily could help on the dance floor.
There should be a fire as the centerpiece of the ceremony, but that shouldn't worry you too much --- only family tend to be required to get close to it.
The wedding feast also tends to be voluminous, so beware tight corsetry
And there is usually a surfeit of bling. You probably can't go too over the top if you tried! Wear jewellery --- even if you generally don't --- or make sure some part of your outfit is seriously sparkly. If you're trying to blend in, gold is the metal of choice rather than silver, which is considered a poor cousin
As for being too provocative, keep in mind that the average Hindu wedding or eveningwear outfit for women typically bares the midriff, as well as a good part of the back and shoulders anyway! AND draws discreet attention to the bust as well! It's hard to go too outrageous versus that, unless you dress for clubbing in a really short skirt and a very plunging neckline on a backless dress at the same time---which you wouldn't for any wedding anyway, right?
