Optimize WordPress Guide Site

I run the WordPress blog https://caramenghubungicsmandiri.wordpress.com/ and would like it to look more polished, load faster, and reach a wider audience. At the moment it is a straightforward information site; I have not applied any premium themes, structured SEO, or performance tuning.

Here is what I would like help with:
• Refresh the current layout so articles are easier to read on both desktop and mobile. A free or lightweight theme is fine as long as it is clean and responsive.
• Improve on-page SEO—titles, meta descriptions, internal links, and basic keyword placement—to help the content rank better for relevant searches.
• Tidy up any technical issues that slow the site down (image optimisation, plugin audit, caching setup).

Optional extras I am open to, if they can be done quickly: a simple logo header, and guidance on what type of content structure could attract more organic traffic in the future. No ongoing maintenance is required right now, just this initial optimisation pass.

Please let me know:
1. A brief outline of what you would adjust first.
2. How long you need to deliver the updated site.
3. Any previous WordPress sites you have optimised that I can check.

I look forward to seeing how you can give the blog a professional boost.