Get a small hammer that you can handle with ease. Any small hammer works, but rubber head will keep hole punch/chisels in good shape.
Instead of buying an expensive, high-maintenance leather knife, use a good quality Stanley knife and craft knife from a warehouse.
I only use Stanley knife to cut my veg-tanned leather and it works perfect.
If you wan to finish your leather work with a great professional look, you will need an edge beveler. This will trim the round and makes it possible to BURNISH. You can buy this on eBay for about $15.
Waxed thread for leather crafting can be very thick and will need a specific needles for stitching. They have rounded blunt tips to avoid scratching the leather. You can purchase a sewing kit from here for $10.
Diamond chisels are essentials if your leather projects require stitching. Different prongs are available from 1 to 10 prongs depending on how big your projects is. $10 on eBay.
If you are making belts, collars or need to set a snap buttons you will need hole punches and setters. They can be anywhere between $5 - $15 a set on eBay.
This will help holding your project in place when you saddle stitch but I only use it when I stitch long distance.
This is a Great tool for dyeing veg tanned leather.
Of all the dyeing method airbrush is the most Accurate, Efficient yet most Economical method of leather dyeing.
For more about Airbrush read - THIS Blog Post.
You can all the tools from leather craft supply shops, but the chances are they are more expensive.
My recommendation is to get them from eBay for cheaper.
The only downside is that some items might be from overseas so it could take a few weeks.