Goggles, swimsuit, kickboard & pull buoy, yes. Here are two key tools to help you swim faster.
Humans were were built to stand upright on the land, not cut through watch like a dolphin. A primary goal of a swimming program is to adapt to the constraints of physics. Here are two essential tools to help.
Training fins give you better acceleration in the water that help drive improved upper body mechanics. A snorkel takes head positioning of out the stroke and enables you balance your stroke equally on each side.
What kind of fins to purchase?
First, two fins to avoid for freestyle training: Swim fins for diving and monofins. While they may be fun to use, they will not help your program.
You'll find all types of training fins on the market. Some look like the ones I had many years ago as a kid. Other look like something from a space monster movie. You can find reviews online for many of these, but in general I recommend two types of fins based on the event you are training for.
Wider and longer from open water swimmers
For the average open water swimmer, kicking serves one purpose, which is to maintain body position (and maybe fend off the pest nipping at your toes). A medium-sized fin with some width are ideal for training. These allow you to employ the effects of a strong kick without effort. Many of our drills are designed to manage body position, establish rotation and drive your hands into a good catch. These fins are essential.
NOTE: Simply Swimming on University in Middleton sells TYR Hydroblades, which look to be a competitor to the popular DMC Elites. For the budget minded, you can buy a pair of regular length (snorkling) fins and cut 4-6 inches from the bottom.
Zoomers for pool swimmers
If you're competing in the pool, from sprints to middle distances, a stronger kick comes in handy. You'll want a fast turnover, and the resistance you get from the fins will strengthen you legs. The classic FINIS Zoomers are renowed for their fit and feel. There are other short fins, but I cannot comment on their value. If you just want a good pair of training fins for lap swims or fast training close to an event, Zoomers are the pair to buy.
Why use a snorkel?
I have used the FINIS Original snorkel for several years and would recommend something similar. All the other swim gear companies offer something similar. Be sure to get kind thats sit in the middle your forehead and not the side type you'd use for snorkeling around tropical fish.
Why use a snorkel? First, I strongly encourage swimmers to master bilateral breathing, as it helps to balance out your stroke. You may not want to use it in a hard set, but you should learn it during drills, warm-ups, the first few sets in a build, and warm-downs.
That said, turning your head to catch you breath is going to change your stroke. You'll even is see it videos of top swimmers like Katie Ledecky, who drops her shoulder on the breathing side more than the other side. Many drills are better performed with your head down all the time, and catching a breath can disrupt the drill.