Using OLED display?

To use the OLED display SSD is it really just as simple as connecting to D3 and D4 on ESP8266?
I have no success with this, including with/without the BME280 configured or connected.
There is no sign of any display, and many times the board hangs.

I can see the AZDelivery SSD1306 board Im using

Has a resistor to select 0x30 or 0x3c - which should I use?

I miss the (2x) 10 K pull up resistor, most of the time it works with no pull up resistor but the IIC bus get errors, most sensors (BME280) has pull up resistor on board
I have OLED display from Ali with no pull up resistor.

Can you see on serial or debug “output values to display…”
Check the BME280 sensor and look at serial or debug “Trying BMx280 sensor on 76 … found”

If you have not found
Trying BMx280 sensor on 76 … not found
Trying BMx280 sensor on 77 … not found
You have probably a IIC bus problem (D3 =>SDA D4=>SCL)

Thanks Fred - I was using on a breadboard, and I think some loose connections!
I removed the BME and connected the OLED directly to the ESP board and it worked, so plugged everything back into the breadboard correctly and securely and it still works, with BME etc.