Well if you're determined to do this then really there are no special tricks to know about except:
If the house is rendered externally you may have a problem getting the new windows in.
The current window boards may be glued and/or pinned to the old windows.
The current window boards have a tongue on them which has to be removed if you're fitting upvc as the upvc don't have a rebate for this.
Egress hinges are need upstairs in certain locations for fire escape.
Trickle ventilation may be needed. Some building inspectors are happy with just the 'night vent' setting on the handle whereas others want a proper trickle vent too.
Cut the old frames out, and don't lever against the outer brickwork or you'll damage the brick quoins on the outer reveal.
The new windows may be slimmer so you have to decide whether to bring them back to the old plaster internally or keep them in the same position externally as the old ones. This may mean making good to plaster internally.
Making good to plaster internally sounds easy but you may have some of the external brickwork showing in this 'gap'. This can cause damp on the inner plasterwork if this is not done properly (capilliary damp).
Access? It is usual to replace windows from the inside but you will need to get to the outside of the windows too for glazing. Is access easy?
Big sashes need 'heel and toeing' when fitting the glass.
How do you intend to fix the frames. Fischer type fixings?
How's your siliconing? Make a mess of this externally and you have spoiled the whole job.
You'll need glazing packers, the correct width and thickness.
Do the upstairs windows first, then if you drop anything it will only damage the old windows, not the new ones.
Can't think of anything else just now........