The antispam technology we have developed (aka “Botmaker”) uses machine learning and rules to determine new patterns of attack by spammers, so it is not possible for us to describe in exact detail what it takes not to be part of one of those patterns.
In general, you cannot post identical Tweets one after another (you will receive error code 187). You should not post automated replies and mentions as these can be a sign of spammy behaviour under the automation rules, especially when this is on an unsolicited basis as this is likely to annoy users.
You may be able to find a system that works for you through some trial-and-error, but there are no hard limits that I can describe for you that will answer your question.