If you visit the credit page of tripoto,you will learn everything about earning credit.
only single photo,video post will earn you 10+ point but if you write your experiance as trip with that pic then you can earn 70+ point. bit hardwork but fruitful. normally clever players here did the first one to earn credit but tripoto knows it all.
additionally if you stay active in community,you can earn a lot.
there is no rocket science in earning credit, its your involvement that matters here. Don't throw photo,video like garbage in community,own it and credit will be there for you.