Question: If I were wanting to drive i.e. industrial relays which require 24v from a Microchip PIC what would I need to look at in terms of a general transistor circuit (and it's pitfalls when driving such a component).

Answer: 
A very simple and integrated solution may be the [NUD3160](http://www.onsemi.com/PowerSolutions/product.do?id=NUD3160). Basically the same footprint as a discrete MOSFET or transistor but with inbuilt protection for both the input and output.
I personally would follow stevenvh's answer only I would move R2 to the pic side of R1. The reason for this is R1 and R2 are acting as a voltage divider and therefore you are not getting the full pic voltage on to the gate pin of the MOSFET. by moving R2 to the other side of R1 you'll get the full voltage at the gate pin. 
Admittedly the voltage loss will be very small as the resistor values chosen here will only loose 0.003v @ 3.3v so it wouldn't really make a difference in this example but with different resistor values it could make a difference so out of principle I would always put R2 on the other side of R1