a master's degree is always best to have for these postings as many post-docs without any firm grounding on income may pursue these openings as well.
One other thing is your connections. That doesn't mean that you can just waltz in at a lab, work there for for 2 years and ask the PI if they have any open positions. Usually your work ethic will be the most important evaluator. Usually, if your PI hires a lot of volunteers, your luck will be dim as you're a height away from being replaced and that too without any expense to the PI. However, if you work around many people with paid positions/fellowships, you can slide the talk in with your PI prior to your volunteering gig and just slave away for months without any income. Unfortunately, I would highly not recommend this unless you have been unemployed for years and you don't have any good references. Also, usually to witness your work ethic, the PI will ask you to come every single day to their lab and won't really provide you your first fruit of labor until after 6 months or so and that too on a temporary basis wherein you're earning peanuts as is the case in academia. Essentially, unless you are not planning to go beyond your educational situation, your PI will continue to employ you on part-time basis and you won't obtain stability until you go for an advanced degree. What use is it then to be working under such conditions?
I would garner that you invest in a post-graduate certification program where you obtain more skills and possibly get picked up from the screening systems that ask for specific jobs. For your molecular job though, it is very nearly impossibly to obtain without further education unless you are god-gifted with supportive people around you.
