Another good question, because it shows that your prospect is thinking ahead. However, until they are prepared to commit themselves, you don't need to go into a half hour speech about every kind of marketing technique available. In truth, not everyone uses every avenue of marketing in any event. Most people find ways that are comfortable to them and rarely stretch themselves out of their comfort zone. Some prefer to work completely offline, whilst others are prepared to try some online marketing.
So, to answer the question, let them know that once they're on board with you, you will be sitting down with them to design a marketing plan that is a good fit for them but, as a general idea, there is a range of effective and proven marketing strategies that are available to them, from word-of-mouth to online and offline advertising.