Prune early-flowering shrubs and climbers like forsythia, kerria, chaenomeles (flowering quince or "japonica"), Clematis montana and other early clematis that have climbed beyond their allotted space. Cutting back not only tidies up these plants, but also encourages them to form vigorous new shoots which will bear next year's flowers.
Climbing roses have a way of distracting you with their lovely blooms while sneakily sending up great thorny stems. Tie these into the fence or trellis, laying them out as horizontally as possible (to stimulate growth all along the length of the shoot, rather than just at the tip). Don't be tempted to weave shoots in and out through the supporting structure, as this causes problems later on when they have toughened and moulded themselves immovably into place.