Runecrafting is simple and requires little patience, and in prothieum you should be done training it with in 15 minutes!
Here is what you will need to know.
First, buy some pure essence in the Grand Exchange or from a friend. Then, with a full inventory of un-noted pure essence, head to Max and tele to the runecrafting teleport. From here you will need to make your runes, tele home (::home), and repeat the process. Do any rune you would like, and then at level 65 you will be able to make death runes. The death altar may be hard to find for some, but it's in there! Deaths are the fastest way from 65 to 99, so be patient.