Tools are usually inexpensive and you'll get a LOT of use out of them. Plus, they are just fun because they'll make your at-home-cocktails feel more legit! The tools I use the most are my muddler (for any drink with muddled fruit or mint leaves) and my fine mesh strainer (great for straining homemade simple syrups into mason jars). A jigger is nice for measuring, but you can use any measuring cup! Having a cocktail shaker is awesome, but you can use anything that seals (like a mason jar) if you don't have one. You just need to be creative when you're pouring, so the ice stays in the container.