Scott overlooks one that ought to be mentioned, although it is not completely "reliable" in a sense: increase your bias.
If you know a 15@1 or better mag skill, your bias is 15@; if the world's bias is also 15@, you get +30 to your mag skills--all of them--because of your advanced understanding of magic.
It doesn't work in a world with a 0@ bias, though, because of course you're limited to the bias of the world; if the world's bias is 7@, your bonus is only +14. But if you have a 15@ bias you will always get the maximum bonus the world bias allows.
Also, and independent of world bias, having a high bias means a high positive on learning new skills. Very few player characters ever having trouble teaching themselves to start fires, because the target skill is somewhere around 1@5 and their tech biases are usually in the 8@ to 12@ range, so you've got something between 81 and 125 minus 15, plus BRA and world bias and any other modifiers, and "learns to start fires from sparks/friction/electricity" is usually automatic.
It can be the same in magic, where the high bias skills are pretty easily learned and the low bias ones are automatic.
You can also take advantage of high bias in designing low bias skills, because you know that you have that +30 bonus when you're in a high bias world, so you can allow a penalty on the skills knowing you will still have a solid chance to learn them and to perform them, and if you can kick them up to professional SALs you'll overcome the penalty that way when you're in low bias worlds.
--M. J. Young