The ability to pick up weight from the floor is one of the most “functional” activities one can do, and it is absolutely worthwhile to learn to do it correctly. Not only is this action an unavoidable aspect of everyday life, practicing deadlifts in the gym is one of the best ways to build total body strength as well as bone density. Ideally you should work with a coach 1-on-1 in order to get started with these, but if that is not an option here are a few tips to get you going.
1) Maintain a neutral spine position
The position of your spine should be essentially identical to that of when you are practicing your planks. It is important to avoid deviating far from a neutral spine, meaning arching excessively or going into flexion (which would look like you are slouching). Trying to pick up weights with a spine that is in flexion is a known mechanism for lower back injuries, so you should really be conscious of avoiding this. If for one reason or another you are not able to maintain a neutral spine and also reach the weight on the floor, you should find a way to bring the weight up to you, such as sliding some blocks under it (this is true no matter what you are deadlifting, be it a kettlebell, a regular barbell, a trap bar, or something else).
2) Keep the weight close to you
This is another element that is critical both for strength and for safety. Make sure you set up with the kettlebell or barbell such that it is lined up with the arches of your feet (centered over your shoelaces). If the weight is even a few inches past that, such as in line with the front of your toes, it will be much harder to lift and the strain will go into your lower back. So, make sure to start it off in a good position. Likewise, you want it to stay close to you as you lift. Think of “keeping your armpits closed” as you lift to make sure the weight does not swing away from you, which again will put too much strain on your lower back.
3) Lift with your hips
The strongest muscles of the body are those around the hips, specifically the gluts. When you deadlift you want to find a position that lets you take advantage of these strong muscles and use them for the lift. This will look something like: 1) your shoulders stay higher than your hips, 2) your hips stay higher than your knees, 3) your hips start backwards behind your ankles, 4) your knees may move forward slightly … but not a lot, and 5) your entire foot is planted firmly on the floor and you feel some weight in your heels. A lot of people have been told “lift with your legs” and while the spirit of that is well-meaning, it is not exactly correct. If you bend your knees too much you will likely take your hips out of their strongest position and will probably shift too much weight towards the toes, which could even make it hard to maintain the neutral spine that was discussed in #1.
When training start off with a modest weight and do sets of 5-10 reps to help establish good form. I recommend starting with a kettlebell and sticking with that until you don’t have a heavy enough kettlebell, at which point you would switch to a trap-bar or regular barbell. A good initial goal is to deadlift your bodyweight for 5 reps. Once you have a basic grasp of technique and have developed some strength you will generally want to keep the repetitions per set fairly low (usually 5 or fewer) and gradually work on being able to lift more weight while retaining solid technique. Those who stick with it for a while will eventually get in the neighborhood of deadlifting 2x their bodyweight or beyond.