My main phone, which work pay for directly, has no passcode, so can be interrogated with no fear of compromise. The phone I use for punting has several 'other' uses not just punting, (I wont elaborate), but Mrs T knows of its existence and has no suspicions as 95% of its use is legitimate and non-punting. This does have a passcode, just in case I get a tempting offer. It's on Tesco network, so credit doesnt expire. I have retained the numbers of three WGs, they are heavily coded in the main phone but only know the number of phone 2, and their ID is not easy to spot in 400+contacts.
Also, I try and avoid using sat nav on the phone to find WGs locations, as they store places visited, so I print a map on paper that goes in a bin on completion of the deed.
The laptop is passcoded, so there's no way Mrs T could add a key stroke recorder, for instance, and I use a different browser to my 'normal' one, and this browser deletes everything on close, so should be safe.
Another thing I do reguarly, is a full reset of phone 2, every month, so it erases locations, texts and all sorts.
As a punter you need to keep ahead of the game and not become complacent.