The standard tyre pressures for the original 'Bias Ply' tyre is 33psi Front & 36 - 41psi rear depending on whether 'solo' or '2-up'.
I think I generally stuck to that until I changed to radial tyres, and now I run 36psi front and 42 psi rear, which is common for may bikes with radials. (I run around those pressures in all my bikes - including the F6C Valkyrie whose original tyres ran at 30psi).
I read an article several years ago which stated that the main manufacturers assumed those pressures when designing their motorcycle tyres - it seems a good place to start.
Of course tyre pressures should be set 'cold' (i.e. before you've done any running on them) as the pressures change in use.
Theoretically you can 'optimise' your tyre pressures by setting the static pressure (Cold) then going for a typical run and re-measuring them & checking them when warm and considering the increase in pressures - this is fine, but will vary according to ambient temperatures (weather) and the road conditions you are operating on .... so if you see anyone waxing lyrical about using that technique & seeing a real term 'advantage' on the road, then I can reliably inform you that they are only fooling one person (Themselves). Manufactures recommendations for O/E spec tyres or tyre manufactures recommendations for their tyres on a specific bike are what have been researched as being the best for general use. (This may make an allowance for 'solo' & 'two-up'/ 'with luggage' riding). Tyre manufacturer's websites can be helpful - but they all have 'jargon' to promote 'features' of their tyres. The main advance in bike tyres is the 'dual compound' or 'multi compound' tyre - with the main advantage applying to the rear tyre to prevent it wearing excessively in the middle where the bulk of the power is applied hardest. 'Squaring off' being the usual issue that spoils the feel of a bike.
Recent Radials I've tried & liked for general use are Bridgestone T30, Michelin Road Pilot 3 & 4 (I have RP3s on the VX as they don't do an RP4 for the front - but they are a big improvement). There are Dunlop Sportmax on the XR, these had good feel but the rear was shot in less than 3000miles from new & now has a Road Pilot 4 GT on the rear (Which I'm bedding in at the moment - but it has a good feel to it. Avon Viper & Venom for the Valk
One thing our 'gang' noticed with Michelin Road Pilot 3 & 4s is that the rear tyre tends to throw road gravel & if you are following someone who's bike has RP 3 or 4s don't get close to their tail, & ride to one side of them if you are on a road that has been recently 'chipped' or keep well back from them when they are overtaking, as light gravel deposits can build in the centre of the road !
Hope that might help !