If you are building a site that has the potential for information that will never age and remain useful for your audience, you have the opportunity to create what is known as evergreen content. It's important to carry out extensive keyword research before planning any evergreen content for a site like this, as your site could hugely benefit from the proper usage of keywords within such content.
Use hashtags (#) to link your posts to other posts that also contain the hashtagged word. For example, if you owned a shoe store, and you wanted to advertise a flash online sale, you could post the sale information to Twitter and use hashtags like #shoesforsale, #shoesaddict, #sneakers, and #footwear to get your post into a larger group of posts related to shoe sales.
The products and services you will be promoting to your audience must be relevant and good quality. Make sure you believe in them and know everything about them, because this will be crucial to you delivering the sales pitch to your audience. You need to build trust with your audience so make sure the products and services you choose to promote are trustworthy enough.