The number of guests and level of formality should be established early on - this might affect the choice and style of reception venue. For example, a smaller venue may be required for an afternoon reception with canapés, whereas more room is needed for a full sit-down dinner.
There will be different priorities and considerations for an intimate day with under 100 guests than for a large wedding catering for, say, 175 people. Remember, too, the more guests that are invited, the more the wedding will cost.
Some couples want an intimate day with only very close friends and family, others decide upon a huge wedding with masses of guests. The decision on whether to invite children also needs to be made. Frank discussions with everyone involved - especially those paying - should be had early on.