Be aware that Smithing skill demands lots of RuneScape Gold running. In the course of training, you'll be visiting many locations like Port Phasmatys, Ardougne, Lumbridge, Falador, Al Kharid, Wilderness so getting products that boost the process (eg. Graceful Outfit) may result in higher xp/hour.
In general , when you start any ability from scratch, it's better to undertake a quest associated with this skill to gain quest experience. By completing the Knight's Sword quest that takes just 10 minutes, you have the opportunity to earn 12 725 Smithing Experience which will get us from level 1 to 29.
All you need to do is start at level 10 is Mining. So the requirements are low and doing this quest will surely be more efficient than traditional training methods. Furthermore, if an experienced player, with a level 20 or more in Magic or level 20 in Mining and level 20 in Crafting it is possible to finish both aspects of Elemental Workshop quest.
This will take you straight into level 35 , without worrying about other Smithing methods for leveling. If you're looking to continue your questing, you could also complete Giant Dwarf quest which later will be required for the other methods. There's also Recipe for Disaster, Devious Minds, Cabin Fever, Elemental Workshop II, Family Crest, Fremennik Trials that you can finish for fastest experience. Remember that all of this quests are exclusive to members and f2p players can't complete them. Sadly neither free to play quest rewards players with Smithing Experience.
LEVELS 29-40 IRON ITEMS. In this bracket, it is important to build the finest iron items out of iron bar that you can - like Iron Platebodies. Achieving a level of 40 should be done in a matter of minutes with about 1000 bars of input. Like I said before, the most effective place to do this is in the western part of Varrock so begin crafting your pieces of Armour there.
LEVELS 30 99 GOLD BLAST FURNACE. The highest experience rate you can earn are the smelting of gold bars up to level 40. Blast Furnace minigame where you can smelt gold bars . This is the reason that so many people are doing this. The use of Goldsmithing Gauntlets during this training method is a must since it greatly improves the experience rate and Buy RS Gold gp per hour.