when I was a wee' lil' F2p I usually merchant saradomin skirts or full runes. But there is still, another way! You could get around 10,000 essence and make airs. I went from level 13 runecrafting to 32 in a day and at like 33 or so you make up to 100 airs per run I got 45 Runecrafting and I make almost 150 airs per rune so wait... 10k of essence and times it by 5 or 4 thats over 40k-50k airs if you have a good level. So whats 40k-50k airs equal in cash 15-20ea thats almost 1,000,000 I made over 17k of airs in a hour one day. Most of the time watching television or listening to music. Hope it helped and mining it will get your mining up to atleast 70, but whatever