Using influencers and bloggers for marketing can be a great strategy. The key to this is using people who are truly influential. It’s easy to buy followers and you can decipher the fake profiles from those who grew their following organically by checking the engagement on their posts in relation to the size of their following. If an influencer has very low engagement with their audience (sub 1%) then it is likely that they have some amount of fake followers. At best, an audience that doesn’t care about their content is not one that you want to invest in as a brand.
It’s also important to select influencers who speak to your target market. An obvious example would be Selena Gomez acting as an influencer for Coca Cola as her audience is youthful and her persona is fun and trendy. She wouldn't be the right selection for a brand like Red Bull who speaks more to extreme sport enthusiasts.
Using influencers usually requires some sort of expense in the form of payment or services/product. If you're a restaurant, you may invite them to have a comped lunch or if you're a clothing company, you may send them jeans for free which they'll take photos of and post using your suggested hashtags. The downside is that you can not dictate what the influencer or blogger may say about your product/business so it may not all be positive as they do strive to be genuine with their audience. So it's imperative that you do your research and check examples of their previous work.