Most of the books you will read are crap, and more like self-help books than anything useful. You don't want to spend time reading this. Focus on your process first, which is the most important thing in sales. Without a process there's nothing else. No book tells you about a process, but here are a few guidelines:
1. Identify your Ideal Client Profile. This is very important: who's the person that needs your service/product and that is willing to pay the most? It can take a few months to define this ICP, because it always changes, but this is the fun at sales. You need to define the role of this person, the organization that he works for, the company size, the industry, and the regions/countries where these leads are. This is the most important step in the sales process.
2. Set up your cadence. How do you approach leads? Via cold-email? or calls? A combination of both works great, and you need a tool to do this. We use SalesLoft.
3. Metrics. Measure everything: number of emails sent per week, number of responses, positive outcomes, numbers of clients acquired, etc. Also, don't forget to set goals: how many clients you want to get in the next quarter? how to hit that number based on the number of leads that you are generating now, and based on your conversion rate?
Sales is a very complex profession, and, as a product designer turned startup founder, I can tell you that it's very fun (and very, very methodological).
Remember: if you don't get leads, you don't get sales. Simple.