Welcome,
As you are in a Cisco Forum, I would like to highly recommend Cisco certifications but that entirely depends on what you want to do or work with as far as technology. If you don't have any or much experience, I would suggest starting with your CCNA and then doing some research to find out what kind of track or more specific subject you like or fits your goals or work objectives.
As far as materials there is plenty of videos on YouTube for the basic certs and Cisco Press books on the subject are very helpful.
You may want to also check out this forum:
https://learningnetwork.cisco.com/
As its geared towards learners and asking questions related to studying and certifications. You can get tons of information there as well! This is only scratching the surface.
Good luck in your studies.
-David
