Those who have had to promote their sites are aware that there are free and paid promotion methods. If the result that will be visible is important, it is better, of course, not to mess with free methods, because they are ineffective. But, alas, it also happens that there is no money at this stage, or they need to be spent on something more important, and not on website promotion. In this case, you can try to promote the resource on your own, using free methods for this.
If the site is very young and there are no visitors as such, it will be much more difficult to promote it. But you have to try. There are several ways in which you can do this. But, they are all ineffective, attract few users, and take a lot of time, effort and nerves.
Forums
The task is that you need to register in thematic forums, actively and for a long time to conduct conversations, participate in discussions so that no one notices and does not identify the sent Cossack. Then, you can slowly start advertising your site, only very, very carefully so that no one marks these messages as spam, the moderator does not block them. You need to insert links, the name into your messages, they say this is such a resource, there is information, or goods at a bargain price, etc., depending on the type of site and what it offers (services, information, goods, etc..)
Social networks
Groups and publics are being created, which will become the official representatives of the site in social networks. You need to fill them out, maintain, attract subscribers and new members, publish posts there with a link to the site. If you do this actively, the number of visits to the site will increase.
Mutual advertising
A good way of mutual promotion, provided that the resources already have at least a small audience, is mutual promotion. You can find a site, the owner of which will place an advertisement for another resource there, for a similar service. Nobody spends anything, but gets new unique visitors. You just need to look for a resource whose users are the target audience of their own. But its subject matter should not be one hundred percent the same, because then it is already a direct competitor, which is unlikely to agree to promote its rival.
Mailing list
Now there is no particular point in doing this anymore, because most of the mail services immediately mark such letters as spam, so the owners of online mailboxes may not even see the message with advertising. But, even if they open them, the chances that they will follow the links of the "left" letter are extremely small.