First of all, you have to find out your requirements. There are a lot of products related to computer which are available in different specifications. For instance, you are looking forward to buy a personal computer, you will require products with different specifications. On the other hand, if you want to buy a server, you will require different products e.g. a bigger hard drive and a more secure system.
You must assess the need for your hardware which will include you monitor, CPU, mouse and all the other accessories. Then, you have to assess your requirement regarding the software e.g. Microsoft office.
It is extremely important for you to buy a good antivirus programme while shopping for your PC. There are a lot of different antivirus software applications which are available in the market. Some are completely free and for some you have to pay a particular amount of money online after their trial period is over. It will be better for you to buy an antivirus software which has good repute and which can keep you PC safe from any kind of virus invasion which can give commands without your consent that can harm your data files or can even delete them.
Most of the software can be downloaded for free from the internet like VLC player. But, some professional software like Microsoft Office, Adobe Photoshop and Dreamweaver require you to pay some money online. Therefore, you must manage your money prudently in order to buy everything which you need for your work.