Quality of a Caller (Da'ee)

I have finished reading an excellent book about the qualities a caller to Allah must possess. For each one, I felt either i dont have it at all or it needs serious work. May Allah make it easy for me. The one quality, however, that really stood out was sincerity. It is sincerity or concern for people that will pull them toward you; sooner or later they will realise your words were genuine and hopefully that will bring about a change in them. While spreading the message of Allah, the most common stumbling stone for me is loss of this sincerity and coming off too pious. Although that has never been my intention and nor do I lose concern entirely; but if my behavior and words do not communicate my intention correctly, then whats the point really. I also feel its tough to "like" everyone, to the extent that you care about their akhirah and sometimes you care so much that you're shoving the deen down their throats. Ofcourse we shouldnt do that. Sometimes i loose sight of my purpose; sometimes it becomes about trying to change them - whereas that is needed too but i have learned that if i just keep the concern alive; the rest will work out bi izn Allah. Now that i have pinpointed my error, I must work on correcting it and thats a daunting task. Im so afraid of my words that I feel I may never be able to speak again, but thats Shaytan trying to stop me and I must fight it. May Allah put love in my heart for His people.