I buy all my cards, wrapping paper, tages, ribbons etc in the sales between christmas and new year. Loads of choice if you buy at this time (rather than at the end of January) and much cheaper, even if you take into account 3 for 2 and the like.
I make as much as I can - Christmas cake, Christmas pudding, sauces etc.
DH' family this year has suggested thatw e do a home made Christmas (taking inspiration from Kirstie Allsop I think!) and although I couldn't be faffed with the whole idea at first, it has saved us lots of money. I have made things like flvoured vodkas, mincemeat, extra Christmas puds and an extra Christmas cake, chutneys and compotes and the like. And I made extra for us, so that was nice!
I buy presents all year round and put them away, and try very hard to resist the temptation to use them or give them before! its very handy in some respects to have presents ready for birthdays and things, though. I buy things which I know will suit my children or friends or family members. I sort of have in mind who I will be giving that present to when I buy it. And I only buy what I really like, not just what is on offer. That way I know that i won't be left with things I don't need or want.
I buy clothes in a size bigger for the children (who really won't care if they're wearing something 'ast season'!) at the end of a season eg last year after Christmas, I bought a size bigger pyjamas for DS, a coat, some tops etc. I buy books, sticker books etc in the sales that are slightly too advanced for the DC and keep them to one side.
I wait and buy toys whenever there is an enormous sale on - it takes some nerve sometimes though to be confident that there will be an even bigger reduction on something that I know one of the children wants! Like ELC are doing an extra 20% off their sale prices atm, and I have bought some brilliant bargains today.
I never pay for delivery - I ask for things to be delivered to a store where possible, or I buy on Amazon, or I don't buy from that store/site at all.
I buy most of my things for Christmas on line. If I see something in a shop that I like, I go home and google it and see how much cheaper it is elsewhere. And I google for a discount code so that i can get an even bigger reduction.
And I always think through what I would like so that if anyone asks me what i would like, I can suggest something!