Climbers flower on new wood so I train my main stems as horizontally aspossible to encourage the sap to flow more easily to make flower buds. In spring, I cut off all dead and broken shoots and any showing die-back. I then remove all the small shoots coming up, down or out from the main stems and any weak and spindly stems and then I give the plant a good feed of general purpose food for foliage and rose fertiliser for flowers.
Each year, on the more established climbers I take at least one main stem out right at the base so the plant puts up new shoots and thus continually renews itself and stays vigorous. I have some newer climbers which are still too young and small to do this too as yet.
Ramblers flower on wood produced the season before so, other than taking out dead or damaged wood in spring, should be pruned after flowering.