You can track adwords conversion in many ways. From Thank You Page tracking to import from analytics, to tracking via Tag Manager. There are different ways, and each has its own merit.
Thank You Page Conversion
Its the oldest and the simplest way of tracking conversions. You just have to download the code from your adwords account and paste it on a hidden page of the website, that is displayed only after completion of a process, you consider useful, like form submission. Though there are other new methods, I still prefer it. It doesn't make your other pages code heavy, its greatest merit. So, if it can be installed it should be your first priority. For websites which doesn't have too many kinds of form submission, it is still the best way to track conversions.
On Click Conversion Tracking
If you want to track clicks on some links or your website points to some third party payment gateway, where installing the code is not possible, tracking click on button is your best bet. For this again, you simply need to download the relevant code, from your adwords account, which is easy, and tag the links after a, like a YOUR ON CLICK CODE href="" with relevant tags. It will start tracking your onclick conversion. However, if your HTML Link contains Target_blank element, this method won't work. That is to say, if your links open in a new window, this method won't track it. Also, if it results into button freeze in some browsers then again you shouldn't install it.
Goal Imports from Google Analytics
This is preferred by Google analytics freaks. There are several caveats associated with it. One, very often it fails to give real time figures. What it gives are corrected after sometimes. Misleading enough, if you are on adwords dashboard. Two, Most often advertisers mix it with other kind of conversions, polluting the dashboard figure. Why not keep analytics limited to GA account. It looks nice, while analyzing it there, but messed up when mixed with Adwords Dashboard. I love to see adwords data inside analytics but hate to see its data on adwords dashboard. Just keep few metrics like bounce rate on adwords dashboard. No need to clutter it with too many imports from there.
Conversion Tracking via Tag Manager
You need to create an account in tagmanager.google.com and download the container code from there. Once you paste it all across your website, you can manage what to track via a configurable dashboard. You can load conversion code via it and it is compatible with many services apart from adwords like analytics, linkedin etc. So, no need to paste code again and again on your website. Simply get some ids like conversion id, label id etc and configure it through web interface. It is very beneficial for tracking form submission if you have different kinds of forms across the website at different places. It can identify forms easily if you are using standard html coding and has <form></form> element, otherwise you may have to tweak it further and let it sniff through some class and other ids. It does make it a bit complicated but its worth attempting. Again, don't forget to tick off the option for validation, otherwise your subsequent pages won't load till all values are passed via this code. Don't go for too much accuracy, because page load time has to be your priority. When this was launched I didn't recommend it to anybody because of this issue only. However, it has the option to deactivate. You can easily track link clicks via this too, even if your link opens in a new window. In this way it gives you maximum with minimum efforts.