What are the points, I should mainly consider, before promoting ClickBank affiliate product through PPC Ads like Adwords?

It's just a lot of trial and error. Try to choose newer products which have high sell rates. Then start small and test the conversion rates of each ad. If one seems to make you more than it's costing you to advertise, then scale the ad campaign up.

I personally think that not a good idea, especially when you are starting with a project. Need money and rather go PPC spend. But just my opinion. Try searching for free traffic with links and stuff.

I would have to agree with Renick08.
PPC is not really profitable anymore unless you are a real pro. The CPC is almost always SO high that you will need a crazy CTR and conversion rate to have a good ROI or to even not loose money! I would suggest you go with other methods like SEO or social media.
Good luck!

Maybe you should consider to get organic traffic to your site instead of focus on paid traffic.

An option would be to make an email capture page then buy some traffic to it, but not from google. You can use bing or buy some space on a webiste. You capture the emails then follow up with some good material and the send the offer.

Another option would be facebook ads even though Facebook traffic is not really that profitable, I would still go with SEO

PPC is not work anymore try another ways.