I got my election card for the first time and voted. Yet, the party lost in Delhi.

Although I know very few supporters of congress, there are several factors I observed:
1. Election Advertisement / mass media - Congress was way ahead with frequent ads directly attacking BJP and kind of answering their points against congress. Also, interestingly, the few BJP ads would inadvertently be followed by congress ads junking the BJP one.

2. There are still many "educated" people who do not vote. A major part of the reason is the bureaucracy related to easy change of addresses and new election cards. Your jaagore link may help in this aspect.

3. I found a certain dislike of Shri Advani among many acquaintances, even BJP supporters. This is contrary to my view (I feel he is the most capable to run the nation today) but the fact is that many "perceive" BJP to be lacking in a strong candidate like Shri Vajpayee (at the moment I'll reserve my opinion). This is all based on a created mass perception. I came across the site of Advani but haven't gone through most of it. However, this site (and other such) needs to be publicised so that commoners can read it and interact with a potential leader of the nation. Advani had made comments about Jinnah which, although true, were used by congress to malign him.

4. Many people a) relate BJP to any act of vandalism by VHP / Shiv Sena or even a non-entity like Ram Sene (Mangalore incident). b) have a bad image about RSS.
These feelings hurt the prospects of BJP. Besides, it becomes difficult to convince such people when a) Mr Yediyurapaa (KA CM) says he will not allow "pub culture". b) BJP does nothing to oppose the sheer goondaism of Shiv Sena in MH, especially related to the "north" Indian issue. c) other such cases.
This is perceived by many as support of the BJP towards vandalism. Any number of comments by BJP leaders cannot change this perception.
THIS is a VERY important point. If this is not acted upon, BJP will always lose a share of voters.

5. Corruption - This is less an issue with BJP than with congress. However, the point I'm getting at is: BJP is not perceived to be above board (so people wonder why they should vote for BJP). While the truly corrupt already vote for congress, what is BJP doing to pull the rest of them towards itself? Due to the long innings of poverty combined with corruption, ALL politicians are expected to be corrupt. What is BJP doing to change this expectation?

6. Infighting - Several comments by BJP leaders point to this. This also leads to the feeling in point (3) above - perception of lack of a strong leader. BJP needs to dispense of such thoughts among commoners.

7. Modi - Sadly, since he always limits himself to GJ, many of his admirers do not see a strong candidate in the fray. Also, sadly, due to the media hype of GJ 2002 riots (forgetting everything else that has happened in the nation), many sections dislike him. BJP needs to come out strongly in favour of Modi and defend him. For instance, his visa rejection by the US is played up. BJP needs to effectively counter the claims against Modi and show that mass riots were controlled in reasonable time.

8. Sonal Shah's comments were sad when she was a part of the Obama team. She said she did not know of the brutalities of GJ 2002 riots and therefore, is severing links with VHP. This kind of a statement hurts BJP indirectly.

9. BJP needs to educate the people as to what its view of the nation is. Does it mean that women cannot dress as they wish?

10. As an extension of point 1 - mass media is used by congress very effectively. I used to attend NDTV shows by people like Barkha Dutt. What came out over time (maybe I was fooled initially) was: a) Congress representatives' and sympathetic audiences' opinions are given a plus. b) BJP / Sangh guests are countered by the hostess herself, if not from sections of the crowd. Their sympathetic opinions are killed. It is clear to you and me but what is BJP doing to change the perception reaching a new political learner watching the show on TV?