I used Magoosh for my GRE preparation. Best thing about this is it would ask you to try free trial period of 7 days but it wouldn't ask for any card details initially so you wouldn't have to worry about the money getting debited automatically after the free trial period! But what I didn't like about Magoosh is that we wouldn't have access to every video tutorial in this trial period so that's a bummer! It got video explanation for every thing and once you select the 3 month or 6 month period it
will prepare a schedule for you so you can blindly follow that cirruculum and you can even mail them your doubts if they are not mentioned in FAQs!