What should i go with?

I earlier had success with list building with buying ppc traffic.

Here is what i have done:

I have choose a health niche, and setup a squeeze page then sent ppc traffic to my squeeze page and collected optins and there by got sales. But with this methods, i failed at profits and gain. I.e i spent too much and could not able to see much money left for me as profit. So i left it.

Later, i took the same niche and started a blog and started ranking keywords on google. I was able to rank some low competitive keywords on top and for every month i was able to get 2-4 sales.

Now, i wanted to expand my link building more but could not find guest blogs in my niche...should i go for purchasing private blog networks?

Or should i start over the list building method with ppc traffic?

I had success with both of them. But scared to start the ppc method again and same with seo of taking too much time to get the results.

Suppose, say i have choosen a product related to "hemorrhoids" in health niche. I don't find much forums to rely on free traffic sources to have my signature and start helping others.

I am also planning on trying solo ads, but due to my niche i've choosen, will i get solo ads for any niche i wanted for?

Hoping for a help from you guys...