Generally speaking, most budget-friendly shared hosting companies allow at least 25 addon domains* in one account nowadays but you can never be sure.Some years ago I was careless and signed up on a web host that allows only one domain.
Be aware though that these often come with a much higher renewal price, so be careful before clicking ‘buy’ on that plan that is offering you a sign up price at 80% discount! Unless you are willing to hop between two or three web hosts every two years, there is no way to avoid pricey renewal costs.
If you expect your website to grow really big over the next two or three years then you should consider picking up a web host with room to grow.
By grow, I mean that it is able to offer you better plans.
Nothing is more important than having a 24×7 operating web host, after all, your visitors may come to your site from time zones all over the world.
You need a web host which is stable, both in terms of their servers as well as network connections.