Create Metadata to use your keywords do not use too many keywords in your description.
Use focus keyword in your H1
SEO body content
Image optimization
internal linking
page load time
You should submit your old URLs in search console URL removal or disavow URLs if you don’t want your old URLs. And the other thing is your old URLs are already indexed then you have to go for the permanent redirection option. In my opinion, it will save your losses.