The most common items used to boost your Mining level in Runescape are Dwarven Stout and Mature Dwarven Stout, the latter of which is only available for members. Dwarven Stout will raise both your Mining and Smithing levels by 1 but, as a negative side effect, it will reduce Attack, Strength, and Defense skills. However, unless you're mining in a dangerous location the temporary reduction of these three skill levels shouldn't be much of a bother. Mature Dwarven Stout works in much the same manner, but it will increase Mining and Smithing levels by 2 instead of 1.
Both Dwarven Stout and Mature Dwarven Stout give a visible increase to your Mining level, so you can use these items to enter the Mining Guild at level 58 or 59 instead of 60. Also, drinking one of these items can allow you to mine ores a level or two earlier. The level increase that comes from drinking a Mature Dwarven Stout is longer than that of a regular Dwarven Stout, but it still only lasts for a few minutes. The increase from a regular Dwarven Stout can last anywhere from a few seconds to around a minute. The positive level increase for both of these beverages does not stack, so there's no reason to drink more than one at a time.
There are a number of places in the Runescape world where you can find or buy Dwarven Stout, such as the Rising Sun in Falador. In addition, Dwarven Stout and Mature Dwarven Stout are both tradeable so you can purchase them on the Grand Exchange if you don't want to go to the trouble of finding or brewing them yourself.
A less dependable (and more cumbersome) way to increase your Mining level is by eating brown spicy stew. Depending on the number of spice doses added to the stew, it's possible to raise your Mining skill by 2, 4, or 6 levels. However, it's also possible that the stew may decrease your Mining skill by the same number of levels.
Brown spicy stew is made by adding brown spice to a regular stew. Neither the brown spice nor the brown spicy stew is tradeable, so if you want to use this boost, you'll have to make the item yourself. Regular stew is quite common in the Runescape world, but the brown spice is a little harder to come by – you won't be able to obtain this item until you've finished the Freeing Evil Dave part of the Recipe for Disaster quest.
Continue on to the next page for information on more items that will help you mine faster and more efficiently in Runescape.