Procreate is an excellent tool, especially for beginners in the digital space. It can also be a great tool for those just starting to create! This software comes in with a low price point, however is currently only available on the iPad. It does however allow for working with layers which can be a powerful feature. One disadvantage however, is the lack of transparent backgrounds. This could make manipulating the finished image difficult, especially if transferring to products or stickers.
Photoshop is the industry standard suite for creators. If you have the money to spend, this software is a must. Adobe offers a monthly subscription service that can make it affordable, however it can still be quite expensive, even with the student rate. We highly recommend the software despite the steep cost and learning curve. There is a plethora of online tutorials and videos to help you get started!
Clip Studio - Formerly Manga Studio
Clip Studio, formerly known as Manga Studio is an excellent full featured software. It has been very popular with Manga artists, however has also been used by others in the comic community. The entry level to purchase is a reasonable price, however the full featured software can run a couple hundred dollars. Luckily they offer free trials for both versions!