i think maybe to be successful in cash games the maximum buy in is advantageous? do u agree?
Absolutely. Give yourself that extra edge...in a lot of cases you will start out as the chip leader by buying in max.

It's also important to mention the importance of 'table-selection' and seat selection at this point. I've seen some good threads on that subject in this forum.

Once you've found the right table keep your game in check and stick around for a while. If you're paying attention, after about 30 min. to an hour you will feel more comfortable with the table dynamic and your knowledge of the other players (the ones who have also been around for a while), and you can make your decisions with more confidence.