My tip is to make your lawn a bold shape as that has more impact than something irregular ... round, oval, square etc ... fit the beds and borders around it.
Here's my back garden which is an awkward shape (narrow pointy triangle). I have three circles - one slate chippings, one lawn and small one of blocks, and the rest is borders. The front garden - another circular lawn with planting all around.And the side/corner section - the lawn here is a more irregular curved shape.As you can see my "designs" are simple, heavy on plants and light on hard landscaping and other features. Others will prefer the opposite approach, it's up to you to decide what you like and have the time to care for.