There are a couple of ways you can add links to other peoples’ websites. Since you don’t control their website but they do, then you can’t really go in and add links unless they want it or allow it. So you will need to follow some digital-PR steps to “convince” them to add a link to your website.
Find your local or national business directories and directories, register and add your business by adding your website ( which in most cases automatically turns into a link to your website ), write about your business and keep your text as much as possible, like the three hundred words mentioned in the on-site SEO section above. Add an image and fill in the alt text if you can, in general, try to apply all the on-site rules we talked about, in your own listing in that directory page.
There are some businesses that have more than one websites. All websites are about similar concepts but not exactly the same. For instance, you may have your law firm’s website but have another one about business-related services for law. You could add a link to the business-related website that will point to your law services website. You can do this in an intuitive way, in a way that you can help your users read more and gain more information.
Every business has some “allies” and partners, which have websites. You can ask them to add a link to your website. For instance, if your law office works with a consultancy agency, then you can ask them to add a link to their website where they list their services and in the law section, that points to your law services page.