I guess I’m looking for a few tips to try and move forward a plot better. I feel like hearing some examples could really help, so how have you guys forshadowed a plot? 

Random gossip in an Inn or Tavern.

Warning when dealing with a merchant not to go or do or be somewhere.

built it into the lore of the world.

revealed it in minion argung

dropped it as an obscure prophecy

has it come up vaguely in a divination

used certain words and phrases constantly in descriptions and conversations

had a bird follow them everywhere, then suddenly leave.

made it noticeable that there were no children or pets around

floated red balloons through a random scene

had an object be lying around during a fetch quest, then a few sessions later had someone describe that object as something they wanted, along with some hint about why they wanted it.

Used a sage to casually drop info about the nature of demons whenever they came by (they thought he was a demon for almost six months, then realized it wasn't him and that the exposition was foreshadowing)

I am going to be using stated fears in a build up to an encounter in the next one. THe above cover the stuff that comes to mind immediately from the last decade or so.

My current campaign opened with a double-foreshadowing, which the party loved.

Premise: The local artificer had made an automated slaughterhouse using iron golems, which quickly and efficiently dispatched the giant cattle of the town. They were set up to attack anything large with 4 legs. He also showed them the water pipes he had installed, snaking across the whole town, and the ballistas he had made called Hashbows. The party were shown all this, and got curious as to why. The artificer then asked them to guard his daughter, who was going to help drive the giant cattle back to town. (the golems and pipes are foreshadowing here.)

On the way to the cattle drive, they found strange corpses - wolves, bears, and other predatory beasts, seemingly exploded from inside. They started guessing Slaad (wrong!).

Finding the cattle, there are way more than expected. Whilst trying to rustle them, they injure one, and where the blood falls, a second, fully grown cow formed. They realised this was why the animals had exploded - they had taken a mouth full of cow, and then a cow had formed inside them. (foreshadowed!)

They then realised the golems, if they set to work, would cause a tide of cows (foreshadow no. 1 for the golems!). So they went to the library to work out what to do.

They discovered a dragon lived nearby, which was the last know place of a hero of old who wielded the Cursebreaker, a sword which could break curses like this.

(long story short) they  found the lair and found the silver mine was being periodically electrocuted by the dragon snoring (foreshadowing!), got the sword and a fair bit of loot besides, and legged it.

(edit!) - on the way to the dragon, they encountered a flying mimic octopus they called Squishy. On the way back, they saw a dragon flying after them, and panicked - only for it to be squishy, pranking them. They saw it again later, and didn't panic - until the very real dragon roared!

When they got back to the town, the dragon appeared on the horizon, and they saw the cattle had arrived. The dragon started blasting the cattle, which started multiplying, and the party fought the dragon. During the fight, they used the Hashbows (foreshadowed!), they got electrocuted by the copper pipes (foreshadowed!) and they ultimately killed the dragon by luring it into the slaughterhouse, where the Golems proceeded to slaughter it (Double foreshadowed by the golems!).

There was also an option for them to lure it into eating a cow, which would have been foreshadowed by the exploded animals.

I was so happy with how it all turned out!

For further foreshadowing, I can't go into detail, but I can advise to try and plan the next phase of your campaign, and drop in hints for it during this phase. If you can, drop hints even earlier!

Quote from Bybyroro >>

I guess I’m looking for a few tips to try and move forward a plot better. So how have you guys forshadowed a plot?

 I'm not sure how these sentences go together. Foreshadowing is typically only clear after the fact, so it's not really a device for moving the plot forward. That happens by dropping leads and being clear about the information you give. If nothing else works, you can always fall back on the dangerous thing happening directly in front of the party, or attacking them outright.

One common pitfall for DMs is trying to be subtle and hoping your party will figure things out based on your clues and vague hints. These are never as clear to the party as they are to you, because the world lives in your head. You need to be clear or the party will either miss your clues entirely or use them to come to a very different conclusion than you were trying to communicate.

A good way to foreshadow a major plot point is to take the party through a less extreme or transformed version of the future situation. Like in a movie where Protagonist and his Best Friend are playing a game and the BF wins by sacrificing a key piece, and then later on in the movie the BF sacrifices himself in a similar gambit. Or sometimes it's just an atmospheric thing, like a bad omen foreshadowing the arrival of something evil.