My advise would be just enjoy it. I mainly have leather strap watches. Only one watch with rubber strap for certain wet and dirty occasions.
1) I try to rotate my leather strap watches and let them 'rest' in between
2) I try to wear them not too tight to allow some air space between my skin and the lining to allow sweat to dry quickly
3) Deployant will typically expand the lifespan of the leather as compared to tang buckle (less tendency to bend the strap and create cracks). Having said that, I still have tag buckles on my dress watch as they still look sexier...
Leather straps are natural materials. The longer you use it, the more comfortable it becomes, just like a shoe. Some OEM leather are expensive, but spread out the cost of the leather strap over the number of days wearing it (say a lifespan of 5 years) and it's really nothing. I think it is worthwhile given the comfort and how good it looks.
Needless to say, if it is an expensive watch, the price of the leather strap is usually insignificant compared to price of the watch. If it's for resale purpose, the main criteria is the condition of the watch, not the strap.