League of Legends (LoL) Question: Hextech Crafting - Efficiency

When it comes to hextech crafting in league, what do you consider to be the most efficient way of crafting. What rarity of skins would you reroll, if they are legacy do you keep them and which rarity and what skins you disenchant. I tend to keep all my epic (and above) rarity skins and i reroll anything thats 975RP or less. It doesnt usually other me unless its legacy sometimes or if its a skin I like for that price. Even if its a champ that I dont play I keep epic skins just because I feel like there may be more value (incase i start to play the champ or need orange essence).