What do you plan to blend? Most hand blenders make quick work of soft foods like milkshakes, refried beans and smoothies (especially if the fruit is fresh). Frozen-fruit smoothies are a tougher task. Don't count on your hand blender to crush ice for frozen drinks, though -- reviews say you really need a countertop blender for that, which we cover in our separate report on blenders.
Are you blending vibrant sauces or smoothies? If so, consider color. Some owners choose stainless steel or chrome hand blenders because they say plastic ones pick up stains from tomato sauce, turmeric and the like. Of course, you can also select a color purely for style -- the Best Reviewed Cuisinart Smart Stick CSB-76 is available in 13 different colors.
Do you like more versatility? Pricier immersion blenders (in the $50 to $100 range) usually come with a mini-chopper bowl attachment and a whisk or other interchangeable mixing tool. This turns the blender into a multi-use tool, allowing you to chop small amounts of vegetables and nuts.
How often will you use it? If you only plan to use your immersion blender for the occasional smoothie or pot of soup, reviews say a basic, inexpensive model will serve you well. But if you think you'll use the hand blender daily, it could pay to choose a more powerful, durable model.
Corded or cordless? Some users like the convenience of a cordless hand blender -- but rechargeable batteries can drain quickly, and corded models tend to perform better in professional tests. Still, you might opt for a cordless stick blender if you plan on cooking outdoors while camping, or if you don't plan to use the unit very frequently.
How deep are your pots? If you plan to blend soups, choose an immersion blender with a long enough blending shaft to reach the bottom of your deepest pot comfortably.
We review a lot of appliances, and immersion blenders get some of the worst reviews for durability that we've ever seen. It's not unusual to read in both professional and user reviews about a hand blender failing on its very first job. Buy the best immersion blender you can afford, be sure to buy the right blender for your usage needs, and stick with name brands with good warranties and good reviews for customer service. Also, realize that these blenders are only meant to be used for a minute or two at a time. Expecting to run it continuously for more than that will result in burned out motors and a short shelf life for any hand blender.