Marketing photography is not a one size fits all activity. You need to be specific about your target market - and where you expect to get customers. If you are targeting people for portraits - what is your specific market? Are you looking to photograph high school seniors, kids, business executives, athletes, or even artists? Word of mouth is important - but only if people in your market are talking to others in your market. You want to concentrate building awareness with the people who either are potential customers or people who know your customers. I know a photographer in a small town that sells $450,000 per year worth of senior portraits. It's 75% of his business and his average client spends more than $3000.
Think about whether you have a market or need to attract one. Social media may be fine for showing other students the great senior photos you took of one of their classmates. But it might not work at all for other markets.
You need to build a portfolio of great images that represent ideas for your clients. What makes your images different from any other photographer. Are you shooting outdoor portraits or indoors?
All this takes time. Since your time is limited, you need to be targeted. Choose the channels that fit your audience. If they use Facebook - you use Facebook. If they use word of mouth - you build a network and ask people to make recommendations. If you need an email list - start building it with the people that know you and your photography.
Figure out the business development strategies that work best. Try something 100 times and assess results. If it works, do it 1000 times and continue to assess. If 1 in 100 will hire you, figure out how to either efficiently reach another 100 or increase the odds to 5 out of 100.