It's a bit like cleaning aneglected room. Do the duting and vaccing and a bit of tidying and it looks so much better.
So, tidy away any rubbish and pull or dig up obvious weeds. Cut the grass once air temps get to above 8C and it starts to grow. Treat it to a weed and feed which is a product you can buy at DIY and garden centres. Read the instructions for when and how to apply it. Keep the grass cut at least once a week, going to every 4 to 5 days in the peak growing season to keep it neat but don't ever cut it shorter than one inch as it needs the leaves to feed the roots.
While you're shopping, buy a bag of pelleted chicken or cow manure to spread around the base of all your shrubs and work in a generous handful or two with a small hand fork so it gets mixed in to the top layer of soil and feeds the roots.
Sharpen your secateurs and prune any obvious dead or broken stems from your shrubs and then tidy up the general shape if needed. It's best to wait till after flowering to do any major pruning.
If you decide to dig over any empty or new beds, do it as soon as you can and then add plnety of well rotted manure or soil improver which you can also buy in if needs be. Then keep an eye on what's on offer at your nearest garden centre and plant some new perennials for colour with annuals to fill the gaps till they mature to full size.
Have fun. Sit back and admire.