Build a silo before building any coop or barn. Otherwise you'll need to buy hay for your animals at the start, and Murphy's Law says that you'll reach Marnie when she's busier staring the microwaves oven.
If the silo is full, you can pull out hay from the manual feeders and dump it into a chest. You can use this to build a single silo ever.
Don't cut every single bit of grass on your way, once you have a silo. Leave some spots here and there, so it regrows. A good way to do so is to use the scythe on a full column or row of grass, then leave a small gap before the next column/row.
If your animals graze outdoors (I recommend it), you can protect bits of grass here and there with fences or lightning rods. It helps to regrow the grass faster this way.
If you're a complete newbie: save money for the first Egg Festival, in 13th/Spring. Buy as many strawberry seeds as you can there. Strawberry is a cash crop, and if you plant them fast enough you'll get multiple harvests.
Also, don't ship every single strawberry that you harvest, leave some normal quality (cheaper) to make seeds later on. If you're able to unlock the greenhouse early enough, you can fill your field with as many strawberries as you want right off 1st/Spring of the year 2.
The best season to mess with your farm layout is winter, as you'll have less crops to deal with. "Less" doesn't mean "none" though - be sure to use winter seeds, they're highly profitable.
You can build sheds for your machinery if you want, but I find the best place to put them is inside the coops/barns with the animals producing the raw materials. For example, the mayo maker goes inside the coop with the chicken, the cheese maker with the cows, etc. It economises time this way.