Here's the problem: You know you need a platform (though if you're honest with yourself, you're only about 50% sure you know what a platform is), but you don't know how to get one or what you're supposed to do with it because you don't actually have a novel out there yet.
Sound about right?
I have three things to say about the early years of building your platform, so stick with me.
1. I feel you.
Honestly, I do. While I am an agent, I'm also a pre-published author (in the fact that I don't yet have a book published, but come hell or high water, I will one of these days). If you go back to the beginning of this humble little blog, you'll see a lot of bumbling about, almost no comments, and very few visitors.
Like many in my shoes, I decided to create a blog with little to no thought as to what I wanted it to be. So I dabbled in this and that for about a year before I saw the light. I figured out what it was that I had that other people wanted. For me, it was a background in marketing that let me help other writers learn how to be more strategic in their marketing efforts. For you, it's probably something else and you may not know what that is yet.
I don't have an answer for you, since only you know what you have to offer. Just know that you're not alone. Most authors struggle with how to focus their platform. Just keep at it.
2. No, you don't have to have a massive platform
If given the choice between a good manuscript with an amazing platform or an outstanding manuscript with absolutely zero platform, I'll take the amazing manuscript every day and twice on Sunday.
I can help you create a platform when the time comes for you to really need one. Trust me when I say that some of my clients probably wish I didn't offer so many tips. And I'm not the only agent who can do this. Most agents who've been in the business a while know what an author needs when it really comes time to get your name out there.
What I can't do is rework your book to superior levels. First, even though I consider myself an editorial agent, I'm not all that and a Jamocha shake (seriously, those things are awesome). Second, I don't have enough hours in the day to commit that much effort into every manuscript from all of my clients. I need you to have the awesome product, with or without a platform.
3. Everyone has a platform unless you live in a cave (and even then...)
In really basic terms, your platform is just the sum total of all the ways you present yourself to the general public. So unless you never answer emails, avoid all social media, and rarely interact with people in person, you have a platform. But if you've never sat down and actually thought through what your focus is, your platform is probably a little scattered.
To reiterate, this is okay (before your books sells). But if you are going to do the whole social media, blogging, human interaction thing, shouldn't you make it work to your advantage?
I'm not saying you need to hire a publicist and a marketing analyst to decide what your platform message is. You're not running for congress, here. All I'm saying is, if you are going to spend a significant amount of time interacting with other writers and readers, it would behoove you to come up with some kind of strategy or focus that starts to create the brand of you.
This can be as basic as the tone of your tweets or wall posts. Are you funny, sarcastic, info driven, silly, etc. Are you the kind of person who shares cat vines or pie charts? Figure out who you are and how you want to be seen (hint: these should be the same) and then consistently be that person when you interact with others.
I hope this helps alleviate some of your "I don't have a platform so no one will ever publish me" fears.
For more info on creating your pre-published platform, I really like this article from Rate Your Story on the DOs and DON'Ts of it all.