Don't recommend BTC -> XMR -> BTC method because it is trivial to trace if you don't know what you're doing. And you are now involving a third party. But if you insist on doing it:
Wait at least a day before swapping back into btc. The longer you wait the better. [to resist timing attacks]
Break it up into several chunks. Do not send the same amount back into btc in one go. DO NOT consolidate after. [to resist amount analysis]
Do the first swap (btc -> xmr) on exchange A. Do the second swap (xmr -> btc) on exchange B. [prevents single exchange from having a full view of both swaps]
Do all this behind tor/i2p or at least a good VPN (mullvad or ivpn). Change your tor identity or vpn server for each swap.
Better:
BTC -> XMR -> spend XMR
Don't recommend BTC -> XMR -> BTC method because it is trivial to trace if you don't know what you're doing. And you are now involving a third party. But if you insist on doing it: