Next month I'll be flying to Philippines with my family and since is not usual to find wine in that country, we thought we can bring our own wine (wrapped and protected) on the checked luggage. Is there any problem with that? do I need to declare it? We are thinking of a couple of 750ml bottles per person.
I believe you'll be able to take 2 bottles with you.
According to World of Duty Free (who are one of the big UK airport based duty free companies, so ought to know...)
The following items may be imported into the Philippines without incurring customs duty:
(snip tobacco bits, not relevent)
2L of alcoholic beverage, in bottles of not more than 1L each.
Wine normally comes in 750ml bottles, so two bottles takes you to 1.5l, three bottles would push you over the limit at 2.25l.
I think those limits are per person, and can't be shared. So, if there were two of you, you could take 2 bottles each, to a total of 4 bottles. I'm fairly sure that two people wouldn't be allowed 5 bottles, as while that'd be 3.75l total you can't normally pool your allowance like that.
(The official Philippines Bureau of Customs website says "Liquor and/or wine: two (2) bottles" with no mention of bottle sizes, so I'd suggest going with the lowest option from the two different sources, and say it's 2 bottles of wine or spirits per person, max bottle size 1l, hence 2 750ml bottles of wine per adult travelling)
Otherwise, for taking bottles, they can't be in your hand luggage due to current hand luggage restrictions. They need to go in your checked luggage. Firstly, make sure they won't cost you too much - bottles of wine are rather heavy so it might push you over your weight limit. Otherwise, place them in the centre of your suitcase, and make sure they're both well wrapped with soft material to cushion them against blows, and are in a sealed bag in case of problems (you don't want the rest of your suitcase covered in wine!). If you have two bottles, wrap them individually, so that they can't knock and break against each other. If the bottles are well padded, and in the middle of the suitcase so surrounded by other squishy things like clothes, then you ought to be fine.