Each and everyone of us has their own sales tactics. It's up to us how to use, nurture, and enhance that skills. We read books, articles, and various references but can't seem to get the hang of it. It may seem hard, and it isn't simple either. The hardest thing is compossing the hows and preparing for rejection. Most of us tend to focus on features and benefits and you've been hearing that phrase whenever you search and/or ask someone how to do it.
Not everything works for everyone. Each of us is unique. We have our own special skills and talent, and some are very good at it. If you want to know how to be good at it, is to first discover your talents, your ups and downs, and of cours learning public speaking.
Before we get to public speaking, let me tell you one thing I learned in sales. It's to sell your product by what they need and use the current situation. For example, when you sell a pen (guess you've heard that line a thousand times), you don't start with the features and benefits. Not everyone has the time to listen to your sales talks. When you are asked to sell the pen in an interview, ask your interviewer what are they doing at the moment and what is their job. They need to take notes, and it's very important in their role to take notes. Don't ask if they have a pen or not, assume they don't and tell them they need to buy your pen. Without it they can't do their jib effectively. So, they need the pen. Next typical question would be what's in it for me. Again, don't bombard with the features and benefits, nobody wants to be sold anything, instead use the current situation and use the big picture on how important the pen would be at that very moment. And beseides, applying for a job is already part of sales, you sell yourself to get hired. You use your strongest points, and that's using the current situation. And any follow ups are your features and benefits. We might not be aware, but sales is part of our everyday lives.
Then, listen to keywords when they get interested (and you will know), then that would be the time to use the features and benefits.
And for public speaking, my secret is to read more and aloud. Read infront of tge mirror and glance at yourself every now and then. Try to maintain eye contact at times. It may sound rediculous, but in time when you get the hang of it, it's easy to maintain that eye contact, sound confident so you won't get lost in words. Your greatest fear is rejection and failure, and your worst enemy is none other than yourself.
Don't doubt yourself, if you won't beleive in yourself who else will? No one can stop you but YOU.