You will find the quietest operation to be manifested in the splitting of power grounds and signal grounds.
Ground these items on any convenient PTX (power transformer) bolt using ring terminals. You may solder two leads to one large ring terminal.
Here's what goes on the PTX side:
PTX Center Tap (usually red/yellow, that is red with a yellow stripe) First and second Filter Cap along with Cathode Resistor/Bypass Cap Ground from the board Center Tap for heater aka filament circuit (usually green/yellow) if one exists. Green Ground Wire from AC Power Cord.
Here's how to do the Signal Grounds:
Run a bus (omnibus) wire from the third filter cap (this filter is the exclusive preamp/signal circuit filter) Connect Grounds from the volume and tone pots to this bus with jumper wires from the ground tabs on the pots.
Connect by jumper wires the grounds for the 220K grid resistors and the cathode resistor/bypass cap for V2.
Finally, connect to the bus the cathode resistor/bypass cap for V1 on the far right end of the board. Bend the bus up and solder the end of it to the most convenient ground tab on one of the input jacks.
Input jacks all make ground by virtue of the fact that the shell makes ground when the jack is screwed to the chassis. Star Washers are provided so that all your jacks will make good ground and won't come loose.
making a good grounding scheme