I don't think I would advise going from "btc -> xmr -> btc" because it is trivial to trace by timing and/or amounts and figure out it was the same person with high probability. This would be much better:
1. btc -> xmr -> spend xmr
2. btc -> coinjoin -> spend btc
But if you still want to, you can do a few things to make it much more difficult to trace:
1) Wait at least a day before swapping back into btc, but the longer the better.
2) Do not send the same amount back into btc in one go. Break it up into chunks. DO NOT consolidate after.
3) For the first swap (btc -> xmr) do on exchange A, for the second swap (xmr -> btc) do on exchange B.
4) Do all this behind tor/i2p or at least a good VPN (mullvad, ivpn, safingIO spn). Change your tor identity or vpn server for each swap.