It depends on what you are good at, for example: if you are good at blog commenting then follow the route of blog commenting & start collecting backlinks (blogs must be dofollow for this) which will increase your serps & you will get loads of traffic for your keywords (off course, that's gonna be targeted traffic which is considered best as far as conversion rates are concerned)
that's just an example, you can do whatever method you feel you are good into,
alternatively you can outsource the same to some professional if you have a feeling somewhere that you can't make it or don't have time for all this stuff.