I will usually train a skill to achieve another, related goal, and I prefer training many skills at once over one skill at a time. For example, when I wanted 68 Smithing to put Mith armor in my Skill, hall, I trained not only smithing but also mining (for the ores), magic (superheating steel bars and high alching steel plates) and runecrafting (for the nats). Currently I'm training Farming primarily to clear the seeds out of my banks but also to grow herbs and seconds for herblore, and I'm saving any leftover produce for Cooking.