There are several other morse code signals that will go great with SOS. Sometimes, being more specific helps in almost any situation. Things like CQD (come quick danger) or hospital are great things to learn. As stated above, it is a good rule of thumb to wait for a second in each letter.
The first on the list is “come quick danger” or “CQD”, one of the first morse code signals ever invented.
To signal, do a 1-second flash, then a 0.25-second flash, then another 1-second flash and 0.25-second flash. Then, two 1-second flashes, following a 0.25-second flash and another 1-second flash. Finally, do a 1-second flash and then two 0.25-second flashes.
The second of the list in the hospital. First, do four 0.25-second flashes for the H, three 1 second flashes for the O, three 0.25 second flashes for the S, and a 0.25-second flash following two 1-second flashes and another 0.25-second flash for the P.
Continuing, we have two 0.25-second flashes for the I, a 1-second flash for the T, then a 0.25-second flash following a 1-second flash for the A, and finally a 0.25-second flash following a 1-second flash, and then two more 0.25-second flashes for the L.