Either go to https://summerofcode.google.com and pick up a project you find interesting since SoC projects are known to be more welcoming comparatively. Or check out this wonderful list of projects to contribute to - https://github.com/mungell/awesome-for-beginners . Just pick up a project you find interesting and start solving some beginner/first-timers issues.
For finding issues to solve -
If you want to directly jump into solving issues, visit https://hacktoberfest.digitalocean.com/details and take a look at the resources listed like issuehub.io which can help us find suitable issues through filters like labels.
Find more of these issues yourself by typing type:issue state:open label:"good-first-issue" in the github search bar. Try different labels like - "hacktoberfest", "beginners" etc.
If you are not able to decide a project to contribute to, just start by solving some issues.
Title : Sugarlabs starter issues
Abstract
These are some of the recent starter issues for sugarlabs organization.
Some issues you can look for
Sugarlabs