Hi Alan.
For the front, put the handbrake on, also have the car in gear, apply wheel chocks to the rear wheels and put the jack under the front crossmember, with a flat piece of wood to spread the load. Watch carefully as you go, as there is always possibility of slippage because the crossmember surface is slightly angled. Also, depending on your jack, clearence under the front valence can be restricted, so watch the jack handle on the paintwork! Axle stands can be placed under the front frame "rails" or under the crossmember at the wishbone pivots.
To raise the rear of the car, one of the easiest ways is to place the jack at the centre of the rear axle. Otherwise put the jack, cushioned again with a suitable piece of wood under the forward spring shackle.
I shoudn't have to say that you must use axle stands to hold the car up if you are working on it. Never rely on the jack, though it can be left in place, unloaded as a sort of safety backup. I have also heard of people putting the spare wheel (or a wheel that is off the car) underneath close to the area that they are working on, with the idea that this would prevent the car hitting the ground if a stand were to collapse. Be absolutely sure that the car is firmly held on the stands before you dive underneath.
Sorry if the safety lecture was not needed, but you can't enjoy your classic if it eats you in the garage 
Ed
P.S. any joy with the starter/solenoid yet?
I want my MGB