If you have an S.O. be thorough in not leaving a trail.
Always keep your app history clear, especially the phone and texting apps.
Be aware of what your router and phone bill will store and track.
Always use the incognito mode, and clear browser.
Always make sure your phone location data is wiped.
Never give out your full real name.
Never tell anyone where your live or work.
Have a hobby email and never email your real email accounts from the hobby email account.
On phone and at home use a VPN as much as possible, never do anything from work or through work wifi . . . ever.
Use very different passwords for all your hobby accounts, nothing that resembles your normal passwords (i.e. something your S.O. can't guess at).
Be prepared to deny, deny, deny, and never break.
Always have a reason to be where you are not supposed to be and an alibi for the time you've been off the grid; best to start with a pattern of never checking in, and always being in meetings or busy . . . the less communicative you are, the less your 2-4 hour absences don't look suspicious, the less you will have to lie, the less lies you will have to remember, the less likely you are to slip up.
Remember. It is only fun, if you don't get caught.