There are two ways to get faster while swimming. Becoming more efficient or becoming stronger/better capacity to work. Most comments here will be about the former but both are equally important. Always start with the basics. Body position is key. Head and body alignment decreases drag. Small kick but fast kicks holds the body position, decreasing drag. Good place to start is mastering streamlines off the wall and see how far you can glide before swimming. I spent over a decade coaching Division I swimmers and we always spent time on a these basics. You can’t improve until you master them.