The answers are in the sticky see this site as pointed to there.
http://www.wow-petopia.com/html/skills/talents_tenacity.html
As pet talents are slow to come because you need to be at level 20 and only get the next talent every 4 levels it gives you plenty of time to think about them but i can give my thoughts on them.
You need 3 points in the first tier so at low level you have two choices and that is either more damage or more health believe me it makes little real difference at lower levels . I usually go for "Charge" first and "Cobra Reflexes" as i like the faster attacks but if preferred "Great Stamina" 3 points to get at the "Blood of the Rhino" talent in tier two is probably better as you will probably be going after higher level mobs as a team.
The Boars are my favourite low level pet but bears do have "swipe" so i guess you are going with a bear ?
My suggestion is getting two pets and talent them differently so you can see the differences in the tier one talents , i know some will say that is a waste of time but is the easiest way to see the differences , if you go full BM you get extra points for your pet talents so you can pick up any talents you missed anyway.
As you are going to team up with a priest it really does not matter what pet you use as she can always throw an extra heal on your pet but Tenacity pets do get Thunderstomp at mid levels which is a great crowd puller , and get the heal pet talent not the revive pet one as why waste points when a priest can do it for you.
One last thing is keep 'cower' in the pet bar as i think it still has a habit of turning itself on and that is the last thing you need.
edited to say there are no real set ways to talent pets although i bet some will say there is and all the talents are useful it depends on which way you intend to use them , i usually go for a mix of damage and keeping pet alive.
Edited, Oct 21st 2009 4:35am by sandralover