Cheating isn't an easy task, most men have have gotten caught red handed while trying to play a fast on their girlfriends.
If you want try cheating then you must be very skilled, really dishonest and would need to come up with new ideas so your girlfriend doesn't get a hang of what you are doing:
Inspired by wikiHow, here are ways to successfully cheat on your girlfriend without getting caught
1. Practice: You know what they say about practice making you perfect, it takes a lot of work to be skilled at cheating.
2. Set up different email addresses: Open a private email strictly dedicated to the 'other woman', one your girlfriend doesn't know about and always remember to logout, never save the password too.
3. Register in a gym: Perfect way to cook up an excuse to sneak out and hang out with your side-chick. Every girl wants to see their man trim and slim, so you won't be queried.
4. Never leave history behind: It doesn't mean you should clear everything, that'll make her more suspicious. Just get rid of the most suspicious ones, you can always cook up a story about the rest.
5. No affairs at work: This is a no-no, because it always backfires. Things go bad then she's bound to rat you out to your girlfriend.