Look at a great looking home and the grass is brown or patchy.
It can be a simple fix many times.
Get a good fertilizer and also some lime.
A hundred dollars will cover most all front lawns.
Even if you can't afford to do the entire lawn, do the front...results will be seen after one or two rainfalls.
Better yet, don't wait for the rain, water the grass...
This grass was brown and after 2 rainfalls it looked like this...the fertilizer didn't hurt the flowers either