IT professionals can specialize in many different fields including PC repair, networking, and software development. In many cases these things can be handled by a person that has only a small amount of experience; however there is always the risk that someone can ruin your current system with their lack of knowledge.
For PC repair and maintenance there are a few things to keep in mind. For hardware installation always make sure that you are buying the right parts for your motherboard. A compatible parts list can usually be found on the manufacturer’s website and on the specifications sheet for the motherboard. It is important not to try and force incompatible parts onto the mother board. Forcing something that does not fit can void the warranty through physical damage and destroy your computer forcing you to buy a new one. Also if you don’t understand what you are looking at don’t mess with it. Removing things improperly or adding things improperly can ruin the PC. If you don’t understand what you are looking at it is always a good Idea to hire an IT specialist. For software installations make sure you have the proper operating system. Trying to install applications on an operating system that is incompatible will create incompatibility problems, give you error and not install at all, or not even show up as an executable file. Something that runs on a pc will not necessarily run on a Mac or Linux operating system.
For networking and networking maintenance this is a little more in-depth and an inexperienced person may run into problems. Setting up a network can be as simple as running a wire to the PC and into a modem to get internet, but businesses have a little more to deal with. A large business with many computers requires many more cables, switches, enterprise class fire walls, wireless networks, and in some cases multiple external IP addresses, and servers. Some projects can get so large that is a good idea to draw out a map of where everything is. In this case if you don’t know what these parts are it is best to hire an IT professional.
Software development almost requires someone with know how in programming languages. Some people even equate knowing a programming language with understanding a foreign language. Like a foreign language there is a different syntax and if you have the syntax wrong the computer will not understand you causing an error. If you do not understand a foreign language you need a translator of that foreign language, or in the case of a programming language you will need a professional software developer.