My advice would be to create items, environments, creatures, whatever you want to specialize in and be hired for, create examples. Don't just show off artwork you've done in the past, most clients want to see if you can do the type of artwork they would hire you to do.
In this case, I would also practice different styles. I would most games tend to look for a cute, simple style or something that could be semi-realistic. You can pick the same object and just practice drawing it in different styles. Use this as a reference sheet for your clients and I also use one for pricing as well. So the simpler the style, the cheaper it normally is and usually takes less time to do. The more detailed, the higher the cost and usually more time to create.
Practice makes perfect as they say, and examples are key. Show only your best, what you love the most, not what others have favorited the most. Keep track of how long it takes you to do something. And finally, make sure it's something you want to do. Some clients could have a massive list of items and have deadlines, so ask yourself if you can do that. Can you work quickly and produce good quality the client would want? Are you able to follow a deadline?
Of course this won't apply to every client, but it's good to keep in mind and prepare yourself. If what the client wants makes you feel uncomfortable or you feel is not within your limits, then tell them. Do not be afraid to refuse work if you feel you cannot match up to what the client desires. When starting out, take on work you know you can do.
