The best ways to get dips is do dollar cost average in. Doing an auto monthly deposit will help you overcome yourself!
You will pay taxes when you sell, and shuffling is not productive. Do you need money in the next 3-5 years? Don't invest it, keep it in savings.
I would never trade funds, to be honest. Pick the general S&P 500 and you'll be fine, especially if you don't have time or interest to follow individual stocks. If you want control, research and purchase individual stocks and HOLD them.
Saving regularly is the most important thing! When I was younger I did S&P 500 and the money builds up, it works, it's easy, it's headache-free. US stocks are good, this is the best economy in the world.
Best wishes!!