If you are in the path of totality, go find a spot early on and just kind of hang out - bring snacks and water and a book. If you aren't familiar with the area, download a map on your phone because the cell network might be slammed with people. Don't look at the sun without solar glasses until totality. The moon takes a while to move in front of the sun and the light level gradually drops, but you won't notice it until probably 90% of the sun is covered. Once totality occurs, you can look at the eclipse with the naked eye.
It is beautiful and indescribable and I was profoundly moved when I watched the 2017 eclipse. I will watch the upcoming one, provided the clouds don't cover it.
Once the eclipse is over, prepare to wait for traffic. It might be a while to get out because so many people go to such a small area.
If you go north/west, the eclipse will take place a bit higher over the horizon. If you go to the eastern part/coast of Spain, it will be very low to the horizon, which would maybe suck inland but might be cool over the ocean.