I haven't really been roleplaying for a while now. I use to come here for hours and roleplayed on and off for years. I owe the guild so much. I want to return here and start over but I am worried I'll bite off more than I can chew. What advice and suggestions do you all have for returning roleplayers?

Literally.

The best thing you can do is just hop right in. It'll help you test the waters of your current comfortability and ease in back into writing normally, even more so given that RoleplayerGuild tends to be a slower site when compared to other roleplaying forums such as RPNation. Whereas you might find people posting multiple times a week on other sites, RPG averages around one weekly post per person, personally speaking from my own experience roleplaying here. If you can handle at least one IC post a week, then you're already on your way getting back into the groove.

Personally, I'd suggest finding a Casual RP to join since the section is more or less a hodgepodge of practically everything and everyone at this point. You'll find people of varying writing level and skill there, with hardly any actual post length requirements or concerns towards quality. It's usually "just write a post" there. If you think what you've written is good, then it's good enough to be posted.