Ah, the freelancing feast/famine cycle. This is really easy in theory, but very hard to get off of in practice.
Here's how I've dealt with it:
1. Niche down really tightly. It seems like you've at least narrowed your expertise to the frontend, but do you specialize in certain industries? Sizes of companies? There are so many general purpose freelance frontend architects, so find a way to get more specialized in your messaging.
2. Network, network, network. Service businesses are relationship based, so if you let your network stagnate, you're going to struggle. I set aside half my time each week for sales and marketing, and at least half that time is networking with people or staying in touch.
3. Do things that bring you energy rather than listening to gurus. In other words, if side projects get you jazzed up and you can build them to facilitate your marketing, do that. If writing works, do that. If you like sending cold emails, try that. If you're doing marketing that doesn't even feel like work, it'll be more sustainable.