This has to be done slowly to prevent any disaster by drastic changes in the environment. Ammonia has to be monitored and the water changes should be paused if pH is rising but ammonia not declining. The bacteria need to catch up first. Remember ammonia gets toxic with rising pH. Prevention of course is the best remedy. Regular maintenance of the tank will prevent the old tank syndrome.
Maintenance is essential.
Nutrient control is an important part. Algone is best used on a regular basis as it controls excess nutrients, esp. nitrates. The aquatic ecosystem in its complexity is an interlinked set of variable factors. A good maintenance schedule will keep them in balance and can prevent most if not all problems related to a neglected aquarium.