Welcome to the quilting world! It's a fun hobby.
I think one of the useful tips is to learn about how to *cut* accurately. In particular, when rotary cutting fabric, make sure the measuring line of your ruler is actually *on* your fabric. (If the line is next to your fabric, you will be cutting just a bit too small of piece of fabric.)
Like with any new craft, you will (inevitably) make some mistakes. Don't beat yourself up over them. As you proceed, you will improve and gain increased skills. When looking at something that is less than perfect, remember that most people will looking at quilts at a much further distance, and with a much less critical eye. A quilt does not need to be perfect to be attractive and enjoyed.
Pick quilting projects that make your heart sing. An attractive pattern and lovely fabrics make the work much more fun! As a beginner, don't feel limited to projects that are labeled for beginners. There are lots of folks that have tackled supposedly "advanced" projects early in their quilting careers; It's usually just a matter of carefully following the directions. There are lots of you-tube videos you can watch for learning all sorts of techniques.