By all means, deadhead your roses after they bloom. Any type of rose can benefit from having the dead blooms taken off. You don't say what type of roses you have. Soem shrub roses and old-fashioned roses bloom twice during the season, so deadheading, feeding and watering will help them bloom again. Generally, prune dead or dying branches in early spring. Fertilize with a slow release, granular fertilizer especially for roses. Water near the root, not from the leaves. Deadhead after bloom. Do not prune again until next spring.