One way to promote your business is to send a letter to everybody telling them what you do. The current cost of a second class stamp is 55 pence, which isn’t cheap, but it could be a good investment.
Many businesses will find that this is pointless advice. Direct mail is just too expensive, and not a good way to contact prospective customers. A public house would not do this, for example. It would just rely on passers-by to see that it is there.
An alternative to direct mail is to push leaflets through doors in the neighborhood. This could be cheaper than posting them, and the leaflets do not need to be individually addressed. A restaurant or takeaway food shop might do this, and it is common to receive such leaflets.
Some businesses will need to write to every prospective customer. This is the only way that they can know of your existence. You might have a website, and of course you can include the website address in your mailings, but in general your prospects will not find your website unless you prompt them in some way.
Many businesses might benefit from a little bit of direct mail or leafletting. They may have a slack season, or an end-of-season where they clear out old stock. This is the time to direct mail with a special offer. There can be other occasions where judicious use of a little direct mail can be helpful, and it is up to you to show some entrepreneurial spirit.
If you want your website to have a good placement in a search engine, then you might find that a bit of direct mail or leafletting on the side is helpful. The search engine will know somehow that a placement with them is not your sole source of business, and it may enhance your listing accordingly.