I conducted usability tests on 4 participants, where they walked through searching for an item, making an offer for an item, and posting a job offer. Following each task, I asked each participant questions regarding their overall experience, noting anything they found to be off-putting or particularly difficult. We would discuss their impressions of each flow, and I received feedback for improvements to be made.

Search for Item
Congrats! You've just moved out for the first time on your own and you're looking to furnish your new place. Head over to the For Sale section and look for a couch with the following filters:
Condition: Used - Like New
Budget: Under $500
Seller Ratings: 5 & up

Make Offer
You've found the perfect couch and you're almost ready to commit, but it's a tad over budget. Make an offer for the item for $250.
A day has passed. Go to your Account page to see if the seller has agreed to this offer. If they have, complete the transaction.

Create Post
You're the new manager of a sushi restaurant, and in desperate need of more servers. Create a job offer posting for servers. Select the following categories for the requirements:
Post Type: Offering/Selling - JobCategory: Service - Restaurant/Food

Each participant was able to navigate and successfully complete each task, with feedback and suggestions. I gained helpful feedback on improvements I could implement in the next phase of iterations.
I generally like to sort feedback from testing phases into affinity maps so I can categorize like suggestions and concerns made by participants, and visually discern what areas of the design need more attention towards than other. Although each task had a 100% completion rate, no design is perfect on its first draft. For this project, it was clear that the buying and selling process were areas of improvement.

I took the organized feedback and created newer iterations of the first draft. The most common concern for participants was regarding the visual design and overall information hierarchy. Users had a difficult time distinguishing information on the post preview page specifically.

Version 1
This is the first iteration of the post preview page, which is the final step of the posting process. The feedback for this design mostly targeted the overall information hierarchy, users felt that the information was not clearly organized in a way that allowed them to digest the page's information across first glances.

Version 2
I redesigned the page to make clearer distinctions for information that was prioritized above others, as well as organizing it into sections. Smaller changes include adding an option for users to view the location on map, collapsing the breadcrumbs to save space, and an option to view the seller's profile.

Version 3
Although I only ran a single round of testing for these designs, I made another iteration of the page after discussing with my mentor potential changes that could be made. In the previous version, my attempt at creating hierarchy across information resembled secondary buttons, which might confuse users into thinking they were clickable. I made edits to this, and I also included an option for users to save the post as a draft in case they want to come back to it at a later time.
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Applying Filters
My first design on the left was meant to automatically update the results as the user added each filter, however; users found this to be confusing during the testing phase, as it didn't show a clear state of the applied results. In the revision, I kept the design the same, but added an Apply Filters button to differentiate between the different states of the results in relation to the added filters. Once the filters have been applied, it's clear to users which filters are selected, and can make adjustments easily.
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Adding Clarification
When creating a post on Craigslist, users can include their contact information and are given the option to display their info on the post. Craigslist introduced this feature in an effort to counter phishing bots that would spam sellers. During the testing phase, participants were confused about this feature and wanted more clarification on what showing email or phone number meant. In the next iteration, I included a help button that clarifies information on hover.