Having worked in leather goods at various companies, I have personally dealt with countless repairs that have come in from every corner of the globe. There are a few common themes to the repairs I've handled, and most are preventable. Here's my guide to avoiding expensive repair or permanent damage to leather bags: 1 - Don't overstuff your bag - I can't say this enough. The vast majority of bags that come in for repair have broken handles. Well-made handbag handles are generally reinforced with multiple layers of construction materials, including interfacing, interlining and various thicknesses of bonded leather. Cow leathers are much more durable and less likely to stretch and tear, but luxury customers tend to purchase bags based on how buttery and soft the leathers are, and no leather is softer than expensive, incredibly thin, Italian lambskin. Despite all the best design and engineering that goes into these bags, most of the bags this happens to are made from lambskins that just cannot handle the amount of stress customers put on their bags. That said, if you've purchased a lambskin or goatskin bag, just be careful not to put anything too heavy in there. Or too sharp. Unfortunately, despite the price, a lot of lambskin bags really just can't hold as much as one would think.
2 - Treat your leather right - Bags will inevitably get a little beat up over the course of their lifetime. If you live in a city, riding the subway, going into crowded restaurants and bars, running into taxis when the rain starts to pour, your bag is going to get a fair amount of wear and tear. I don't usually put any sort of waterproofers on at the start, but I definitely treat the leather when it gets dirty. About once every other month, I get all my bags out and use a soft cloth or shoe brush to wipe off any dirt and grime, then I use Meltonian Leather Lotion to clean the leather and prevent it from drying out and cracking. Make sure to test the lotion on an inside portion of the leather first because some dyed leathers can rub off or stain with leather lotions. A basic shoe care kit has all the same tools that you'll need to clean and care for a leather bag. In the unavoidable event that your bag gets caught in the rain, let your bag dry off naturally, away from heat sources that can warp the skins. Just leave the bag in a well-ventilated room on a towel to dry.
3 - Carry a makeup bag - I'm constantly impressed by the number of makeup and fragrance accidents that occur in handbags. Even if you don't mind stained bag linings, a bad spill could actually leak through and stain your leather through the inside. Until cosmetic companies make more durable packaging (those clasps and closures just seem to click open way too easily), it's a smart idea to use a makeup case to hold all your foundation, liquid liner, and Benefit Benetint. Fragrance rollerballs are an incredibly portable alternative to small glass bottles. A cheap $15 makeup case with water-resistant lining can prevent a lot of damage to a $1500 bag.
4 - Store your bags properly - I try to store my bags away in a closet so they aren't cluttering my floor, depending on how often I use the bag. I store bags that I won't use for a few weeks in the dustbag that it came with. I store totes flat instead of hanging. If the bag isn't very structured and won't stand up on its own, I stuff it with a hand towel and prop it in an upright position, trying not to have the leather fold on itself. Bags stored crumpled up can develop unfortunate wrinkling.
In the end, a bag, despite how beloved it may be, is still just a bag, so don't fret too much if it gets a little dinged up while you're living your life. Consider it a well-earned battle scar. You can always buy another...and another...and another.