Ok I will overcome my wedding phobia to pass on some factual information (NB I have no objection to marriage per se.... in fact I think it a very good idea for other people but most weddings these days seem to have got completely out of control and whenever I go to one I feel I am in a remake of "4 weddings and a funeral").
Laws and Customs of the Eldar in
Morgoth's Ring gives information on wedding customs among the Noldor. "
The Eldar wedded once only in life, and for love or at the least by free will upon either part. Even when in after days, as histories reveal, many of the Eldar in Middle-earth became corrupted, and their hearts darkened by the shadow that lies upon Arda, seldom is any tale told of deeds of lust among them.
Marriage, save for rare ill chances or strange fates, was the natural course of life for all the Eldar. It took place in this way. Those who would afterwards become wedded might choose one another early in youth, even as children (and indeed this happened often in days of peace); but unless they desired soon to be married and were of fitting age, the betrothal awaited the judgement of the parents of either party.
In due time the betrothal was announced at a meeting of the two houses concerned, and the betrothed gave silver rings one to another. According to the laws of the Eldar this betrothal was bound then to stand for one year at least, and it often stood for longer. During this time it could be revoked by a public return of the rings, the rings then being molten and not again used for a betrothal. Such was the law; but the right of revoking was seldom used, for the Eldar do not err lightly in such a choice. They are not easily deceived by their own kind; and their spirits being masters of their bodies, they are seldom swayed by the desires of the body only, but are by nature continent and steadfast.
Nonetheless among the Eldar, even in Aman, the desire for marriage was not always fulfilled. Love was not always returned; and more than one might desire one another for spouse. Concerning this, the only cause by which sorrow entered the bliss of Aman, the Valar were in doubt. Some held that it came from the marring of Arda, and form the Shadow under which the Eldar awaoke; for thence only (they said) comes grief or disorder. Some held that it came of love itself, and of the freedom of each fea, and was a mystery of the nature of the Children of Eru.
After the betrothel it was the part of the betrothed to appoint the time of their wedding, when at least one year had passed. Then at a feast, again shared by the two houses, the marriage was celebrated. At the end of the feast the betrothed stood forth, and the mother of the bride and the father of the bridegroom joined the hands of the pair and blessed them. For this blessing there was a solemn form, but no mortal has heard it; though the Eldar say that Varda was named in witness by the mother and Manwe by the father; and moreover that the name of Eru was spoken (as was seldom done at any other time). The betrothed then received back from the other their silver rings (and treasured them); but they gave in exchange slender rings of gold, which were worn upon the index of the right hand.
Among the Noldor also it was a custon that the bride's mother should give to the bridegroom a jewel upon a chain or collar; and the bridegroom's father should give a like gift to the bride. These gifts were sometimes given before the feast. (Thus the gift of Galadriel to Aragorn, since she was in place of Arwen's mother, was in part a bridal gift and earnest of the wedding that was later accomplished.)
But these ceremonies were not rites necessary to marriage; they were only a gracious mode by which the love of the parents was manifested, and the union was recognized which would join not only the betrothed but their two houses together. It was the act of bodily union that achieved marriage, and after which the indissoluble bond was complete. In happy days and times of peace it was held ungracious and contemptuous of kin to forgo the ceremonies, but it was at all times lawful for any of the Eldar, both bein unwed, to marry thus of free consent on to another without ceremony or witness (save blessings exhanged and the naming of the Name); and the union so joined was alike indissoluble. In days of old, in times of trouble, in flight and exile and wandering, such marriages were often made."As for hobbits, when Tolkien was trying to start the Hobbit sequel and get round the problem of having said that Bilbo didn't have more adventures he did consider marrying off Bilbo and worked on the idea of Hobbit marriages being terribly secret and only announced when completed.
Tolkien doesn't mention special clothing but this might simply becasue as a heterosexual male it was not an area of interest.... White wedding dresses are a very recent and for most people terribly unflattering tradition. In some countries and cultures white is the colour of mourning and in other red the appropriate colour for brides to wear which would be shocking! (
colour symbolism)
White dresses became fashionable because Queen Victoria wore a white dress for her wedding. Previously brides wore any colour apart form red or black. Blue not white was the colour associated with purity. And this symbolism is somewhat superfluous in the Elvish context....
Also in less extravagant times it would only have been the extremely wealthy who could afford the luxury of a dress that would only be worn once (which really is quite decadent if you think about it), so poorer brides would simply wear their best dress. This custom was revived through necessity during WW2 when rationing meant that white wedding dresses were not really and option unless the bride had one passed on to her or was very resourceful with parachute silk. Most brides had to opt for a coloured day dress that could be worn again.
Elves made everything to be beautiful and were so intune with nature that I can't help thinking that they wouldn't be so wasteful as to have a dress to be worn once. My guess is they might have a new dress but not wear it just once...