ESP8266 with DHT11 does not serial print values

Another problem could be: DHT is a 5V sensor, ESP is 3.3V.

Many other, better, temp/humidity sensors are available which are 3.3V devices. BME280 is a good one - it can measure atmospheric pressure as well as temp and humidity. But if temp/humidity is all you need, there is SHT21 for example.