It seems not working when seller doesn't ship to my country. Seller says that he can ship it to me if I win, but bidder didn't make a bid. Could I do something to avoid that situation happen again?

If seller confirmed he can ship it, he must remove this restrictions from his listing.
If you can't bid manually due to restriction set by the seller, the sniper can't bid as well.

Please work with the seller to make sure he removed the restriction or added you to the exception list of allowed bidders. There is no way around it if seller blocked you.