Tips on making a good GUI without external software

I was searching for how to improve GUI in roblox studio, but all tutorials use external softwares, i was wondering if anyone could give me some tips on UI Design in roblox studio.

Make good use of UIGradients, UIStrokes, UIBorders, etc. It is possible to make a decent UI in Roblox but its way easier using a free third party software like Figma, that easily lets you export your UI in whatever resolution you want.