How to roll over futures contract

Suppose you have a futures contract that you want to roll over to next nearest
tradable month. You may sell current contract at some point then wait the price going down.
Then you buy in next nearest tradable month or roll over successfully.  But you
get loss or unsuccessful if the price going up.

Avoiding the drawback, you can buy the nearest tradable month contract.  When price rise,
you simply sell current contract.