When you get the battery, put it into the phone and plug in the charger. Leave the phone off. Wait until the phone tells you to remove the charger.
Then unplug the charger and use the phone normally (whatever is "normally" for you - light usage, heavy usage, whatever.) DO NOT plug the charger in until the phone tells you to. Then turn the phone off, plug in the charger and leave it in until the phone tells you to remove the charger.
Do this 3 times - 3 charges, 3 uses without charging. (It's called conditioning the battery. And I disagree with those who say thta "modern" LiIon batteries don't need to be conditioned. Whenther they do or not depends on a number of things, like how they were stored, how long they were stored between the time they were made and the time you got them, etc. Conditioning batery can't hurt it, not conditioning a badly stored battery can.)
1 Year is MUCH too short a life for a battery. You should get t least 18 months, but more like 2 years. If you really treat it right, usually recharging it when it reaches 50% charge, never leaving it in a freezing car or a car with all the windows shut in a 100 degree climte, it can last a lot longer. I have batteries older than 10 years that still give me nearly full life between charges.
BTW, an extended battery lasts longer between charges - but it also takes longer to charge. The chemical reaction works the same in both directions - longer time between charges, longer charge time.