It's getting easier and easier to get started in robotics and build a robot. If you are still hesitating, or don't know how to do it, here are my top 2 advice:
1- think big, start small.
You need to have a goal in mind when you start your hobby. It will help you keep focus and let you know what you need to learn as you go.
2- Just do it!
Even if you don't know what you're doing, you have to get started somehow. Otherwise, you won't learn anyway. Your first robot may be horrible, not even working, but then you'll learn to correct that and in a year or 2, you'll become a pro.
But if you don't start today, you will never make any progress.
Here, you will find resources to get you started, and how to choose/find parts and supplies. Later, I will add some robot projects. You can be the first one to know if you join my mailing list: Robot Tips. As the name implies, you'll also receive regular tips for building robots, about robotic news, and home robots.
Subscribe Now to Robot Tips
The first thing you need to do to build a robot is choose what platform you want. You can choose to buy a robot ready to be programmed, or buy a kit, or make it from scratch. What's the best way to start? It depends on you, of course. Click here to read the pros and cons of each, and choose your first robot.
Check here to find out more about robot arm kits. They really are a great choice for newbies. That's what I started with, and I had lot of fun with my kit. You also find my secret technique to get your first robots for free!
Finally, if you're not so much into AI, you should check here why making a remote control robot can be really cool.
When you build a robot from scratch, using Arduino for example, you will need to choose some sensors and actuators to make your robot interact with its environment.
You can check this page on robotic sensors. I describe all kinds of robotic sensors that may be useful for your projects, as well as those you need for more advanced ones.
Read this page if you need an introduction to the 3 main types of robot motors. You will definitely need some if you want your robot to move!
Now there are also a lot of things you can get for free. I share my techniques to get free robot supplies on this page. That should help you lower the cost of your first robots by a margin.
Now, whether you build a robot from scratch or just by a complete robot, you will have surely have some programmig involved. Here you'll find the basics of robot programming architectures, to help you organize your code efficiently.
Also, you may consider using robot simulation software at some point. They will become very useful to design your robots or test complexed algorithms, as they can speed up testing.