have a long, hard think about what actually will be important to you after the day. I had no idea and rushed my wedding plans so we would have time to marry before a move to the States, as we needed it for visas (sounds unromantic, but we were engaged 5 years).
Things I bought at vast expense that were a total waste of money:-
The cake - 5 layers, each a different flavour - looked nothing like I had hoped, and cost $350GBP and I didn't even have a slice - the venue threw it away before next morning too, nobody I spoke to even got to try it because the 3 course lunch and then buffet had filled them up.
Make up artist:- I am always running late, and because I had to catch a bus to the hotel (my own mother didn't offer me a ride and we were skint after all the wedding expenses - oops - I threw up on the bus as had morning sickness too) I was too late after hair appointment to get my make up done. There was a very angry woman who looked like that huge blonde woman off How Clean is Your Home making grumpy clucking noises as she managed to shove a tiny bit of blusher on while I breast fed my daughter... Could have saved $50GBP right there.
Home made wedding invites:- Cost about $300GBP!!! Oooops, thought I was saving money, didn't realise how fancy and OTT I was going with them, wasted about two weeks making them all, got through a dozen pairs of those fancy edging scissors and took so long some guests only got the invites on the day of the service!
Dress:- I had mine made for me from a design I drew. I thought it would be cheaper than going to a store and I was shy and embarrassed about trying on dresses in the shops. The dress ended up being the biggest expense, crazy OTT and I didn't love it as much as I should have for the price it cost. I have always regretted not just getting the red one I really wanted.
Thing I didn't get which was a good saving:-
Wedding cars - we didn't bother at all as church and hotel were oposite each other. Was a bit of a pain as I was 40 minutes late for the wedding and MIL had to shove my dress into her tiny Vauxhall Astra with skirts over my head, filling the whole car... bridesmaids had to leg it over there holding their petticoats up and arriving breathless... but it saved about $500GBP and weren't missed at all. A taxi would have done!
Thing I wished I had researched better:- Photographer. I chose a guy off ebay and paid $600GBP for all the photos, with a 50 photo album for us and two parent books of 20 pictures... well, when he sent me the photos I didn't like them :-( Any of them. So I didn't get round to choosing which I wanted in the books, and now 6 years later it is too late and I only have the computer albums. We wasted that money which could have paid for a good photographer.