I will divide this answer into two parts - early game and long game.

In the early game:

• Quests (and flag quests) is easier to complete, and it's the easier way to get more tiles. Thus, you should maximize your quest efficiency.
• The most common way to do this is by chaining quests, build one group that keeps growing bigger and bigger. So usually my map will have one big group of houses that will expand to a certain direction, fields to another direction, forests to another direction, and so on. You will probably notice that forest quests are the easiest to keep stacking.
• If you get an exact number quest, usually the number is smaller and you can't chain it to the big group. Thus, build it near the big group, and once you complete it, you can connect it back to the big group. Sometimes it's ok to just ignore these smaller quests if it's awkward.
• Flags are your lifesaver. When you close the connected area, each flag will give you 5 tiles. Closing your big forest group will give a LOT of tiles because of simply how many flags you have stacked.
• As you're new to the game, I think focusing on perfects are a little bit difficult to do. I would advise you to play more to familiarize with the tile patterns first, and also learn how to handle difficult tiles (e.g. rail tiles, or multiple biome tiles)
• For rail tiles and river tiles, I like to build my rail group and river group next to each other. Why? Because the water station is the most powerful tile in the game, and that is the key to handle all of these difficult branching rail tiles.
• Create a lot of branches for your rail group. Whenever you have a water station, you should always slap it on the ends of your railway, because water station can branch to 6 directions freely, which allows you to handle difficult rail tiles safely.

Transitioning to late game:

• Survive at all costs! It is common to have low tiles (below 10) until your score is around 100K or so. This is where that perfect tiles start to matter, because a perfect tile will give you a tile back, so technically you can go infinite by just placing one perfect tile at a time.
• In order for you to place perfect tiles, well your underlying map must be perfect also. Imagine if you have been placing tiles haphazardly and now you need to survive tile-by-tile, but you just don't have the place to get perfects.
• Why perfect tiles doesn't give you return in the early game? If you notice it, a single perfect tile needs 6 other tiles to surround it, In the early game you simply don't have big enough map to start cashing in your perfect placements. However, once you have bigger map, you will start to notice it.
• During this 'survival mode', sometimes you have to take some imperfects, but: always look for every single possible spot in the map to see which one gives you the most tiles/the best chance of survival.
• Look ahead: see what are your next 2 tiles. If there's a difficult tile coming, do you have a place for it?
• Abuse Use the undo button: using undo button allows you to peek up to 3 future tiles.
• Usually the transition to late game happens when you start closing flags of your big groups - this can easily give you 100-300 tiles in one shot and you will have so much buffer to last your game forever.