I'm going to get married next month, and I want to know how to choose the wedding cake？

You need to contact bakers ASAP!  Many bakers will not book with only a month's lead time or are already booked. Once you find one who has an opening you need to schedule a tasting and talk design.  Good luck!

With a month to go, I think you'd have to forgo the tasting.  Find bakers, call them, and if they have a slot, I wouldn't be fussy and just book them!  Some of the premium supermarkets here do wedding cakes but I think even them, you have to book several weeks in advance.  Good luck, you'll need it.

Sometimes I will have an opening but usually I'm booked 6 months to a year out.  I would start looking for someone straight away and have a design in mind.  Look through Pintrest to find some ideas and think about what your reception is going to look like so that your wedding cake flows with the decorations.  Good luck!