If you are new to Power BI or just looking where you can keep up to date with the technology, the following links are a great place to start. (Updated March 2021)
The best place to start when learning to develop Power BI solutions is to review the logical architecture your Data Visualization projects will have. There are many moving parts and pieces to a Power BI solution, especially when looking at the varied data sources you can use. From on-premises to web-based, from public to confidential, you must make sure you expose your data securely. Having a good clear architecture will help you achieve a not only a good solution but also a secure one. The following article will show you how you can architect your own solution.
There is a very active community around PowerBI with many sites specializing in different aspects of the product. The following 4 resources are ones I always fall back on recommending that provide both beginner and advanced users learning resources.
The date dimension is the table that controls your time analysis and the most important to get right, especially with PowerBI and other visualization tools. Having various tags and descriptors that aid in your analysis gives your end users several options in creating their visualizations in addition to a base for DAX time intelligence calculations.
If you have an excel table that is built for data entry, it may not be in the best format for data analysis or your data model. By using Query Editor, you can keep the original table and create a version that you can use for analysis as a dimensional fact table.
How do I make it easy for the end user to move the source Excel File around while making it easy to update the source location in PowerBI? Query Parameters solved that issue making the solution a lot easier to maintain.