How to build a Tableau Portfolio
If you don't have access to Tableau Desktop, download the free Tableau Public tool. It's completely free to use to practice your skills and publish dashboards. The only downside is that you cannot save your work to your local drive, like with the full Tableau Desktop installation.
If you're a university/college student check out Tableau for students and get a full Tableau Desktop license for FREE.
Sign up for a Tableau Public account. You will use this to host your visualization portfolio.
Go to workout-wednesday.com and check out their Tableau tab. Workout Wednesday is a free community challenge where you are given an exact report/dashboard to replicate to test your skills. There's a new challenge posted every Wednesday and the solution is usually posted by the weekend. There are over 200 challenges so you will not run out of practice material any time soon. I recommend you complete their entire Tableau Essentials section before moving on to the other challenges. Publish all your work to your Tableau Public profile.
Go to Makeover Monday and go through their datasets. Makeover Monday is a challenge similar to Workout Wednesday, except instead of telling you exactly what to do, you are given a dataset and an original visualization and you are tasked with exploring the data and presenting it in a different way. This challenge is completely free-form and there are no wrong answers. I really like it because you can also see other people's solutions and get a feel for what makes an effective visualization. There's also over 200 datasets available so you'll have plenty of material to work with. I recommend you do at least 10 of these and put them on your Tableau Public profile.
Create your own dashboards. Now that you have a profile filled with Workout Wednesday and Makeover Monday content, it's time to build your own dashboards with either data you find interesting, like an analysis of your favorite sports team performance over the years, or an analysis of your own data like steps, or sleep. This will give you the closest practice to being an actual data analyst because when you are in a DA role, you should be the subject matter expert on the data you are working with. That's why picking a topic you are passionate about, like sports, or picking topics you know a lot about, like your steps and when they were low because you were sick or abnormally high because you were on vacation, will yield a much better analysis than with data you don't know much about.