also as for what expansion to get as a beginner i like seaside a lot. but thats on yourself to decide
In my opinion, Seaside is not very good for beginners. It has some concepts that are rather difficult to understand when you don't have general experience of the game.
(Remembering myself, that didn't quite like Tactician and Haven when I first saw them, kinda thought that duration cards were not good for engine -what a hilarious mistake there!
- and that Treasure Map and Embargo are for extremely rare cases. Also Native Village is generally quite hard to handle.)
I would recommend buying sets in the following order, starting from the Set that includes cards that are easier to understand and more fun to play with, and moving to Sets that include cards that are not so easy to understand and handle and can create some more complex strategies:
Dominion (Base), Intrigue, Prosperity, Hinterlands, Alchemy, Seaside, Cornucopia, Dark Ages, Guilds.
(Alchemy could possibly be any slot between Intrigue and Seaside on the list above. I remember that i liked very much, after trying out Base and Intrigue. I really liked the Potion theme. But, some of the cards are not so easy to play with, so i put it after Hinterlands on this list. But, this is generally the right order in terms of going from simplicity to complexity.)