Is there a order i should enchant an item lets say like a god sword to help save on xp should i combine any books first or do the books one by one
if so what is the order for god swords

Combine books with sword one at a time with the highest level enchants first.
eg. Sharp V, Unb III...
you get the idea.

This is a bit complicated to answer so here's a short answer and then the TL;DR:

Short answer:
Combine books in pairs first, then add them to sword or whatever doing the most expensive first.
If you do them like in the pic below it should use the least total levels, and have the least expensive steps.

(numbers might be a smidge off)

TL;DR
Anvil costs come from two things; prior work cost, and enchantment cost (which are added)

Prior work cost starts at 0, and each time you do any anviling doubles and 1 is added. So it goes 0, 1, 3, 7, 15, 31, then is too expensive.
If you combine two things the prior work cost for both is added.
If you do books in pairs first you avoid having to pay really high prior work costs (pic above anything above 7)

Enchantment cost is the level of the enchantment x some multiplier. Multipliers seem to be random, you can find them here if you really want to.
The enchant cost is only calculated for the enchants you're adding (second anvil slot). So when combining books you want to put the cheap ones in the second slot.
E.g. looting III costs 6 and unbreaking III costs 3 so we do Looting + Unbreaking, not Unbreaking + Looting.

By combining books in pairs before adding them to weapons/tools/armour you do pay the enchantment cost of some of the enchantments twice, but that's made up for by the saving in prior work cost if you do it right. If you can get everything right you can make any fully enchanted gear without any step costing more than 15 levels.

Anyone still reading?

Yes

@NutjobBob This is a bit complicated to answer so here's a short answer and then the TL;DR:

Short answer:
Combine books in pairs first, then add them to sword or whatever doing the most expensive first.
If you do them like in the pic below it should use the least total levels, and have the least expensive steps.

(numbers might be a smidge off)

TL;DR
Anvil costs come from two things; prior work cost, and enchantment cost (which are added)

Prior work cost starts at 0, and each time you do any anviling doubles and 1 is added. So it goes 0, 1, 3, 7, 15, 31, then is too expensive.
If you combine two things the prior work cost for both is added.
If you do books in pairs first you avoid having to pay really high prior work costs (pic above anything above 7)

Enchantment cost is the level of the enchantment x some multiplier. Multipliers seem to be random, you can find them here if you really want to.
The enchant cost is only calculated for the enchants you're adding (second anvil slot). So when combining books you want to put the cheap ones in the second slot.
E.g. looting III costs 6 and unbreaking III costs 3 so we do Looting + Unbreaking, not Unbreaking + Looting.

By combining books in pairs before adding them to weapons/tools/armour you do pay the enchantment cost of some of the enchantments twice, but that's made up for by the saving in prior work cost if you do it right. If you can get everything right you can make any fully enchanted gear without any step costing more than 15 levels.

Anyone still reading?

That is extremely useful, thanks!

I actually believe it goes to 37 before it's too expensive, I vaguely remember adding an enchant to a sword at 37

@Abbasilol no xD

Fuck you

@_Confederacy_ Yes

@Cileklim That is extremely useful, thanks!

and hey thanks!

@Cellexya The anvil goes up to 39 before its too expensive. I was talking about the prior work cost though, which after 31 would be 63. Which means you can anvil something up to 6 times before it costs too much.

Ah I see

If you manage to get the 63 levels would it still be considered too expensive? And the 126 after, then the 252 after that?

Yes, after 39 it's too expensive and won't let you enchant

@_Confederacy_ If you manage to get the 63 levels would it still be considered too expensive? And the 126 after, then the 252 after that?

It would be 127 and 255.