Bangkok is generally safe for tourists. Scams are the main concern rather than violent crime. The most prevalent: tuk-tuk drivers offering suspicious cheap tours that end at gem shops, 'closed temple' scams where strangers redirect you from temples (always open), and rigged games near tourist sites. Simply ignore unsolicited approaches near major sights.
Traffic is genuinely dangerous — Bangkok has high road accident rates. Use BTS Skytrain and MRT metro rather than street-level transport where possible. If taking a taxi, ensure the meter is running. Grab (the Southeast Asian Uber equivalent) is excellent and eliminates negotiation. The red-light entertainment districts are generally safe but operate on different rules.