Interesting thing about EQ is that you have a lot of choices on how you play your character's progression.
Like to get the top level as soon as possible? It is called power leveling and you can fight non stop to move through the levels as fast as you can with help.
Like to take a break from combat and get experience from quests? Game has a lot of quests available (some better than others like the newbie armor ones), especially at the low and high levels.
Like to get a well rounded character? There are tradeskills to work on throughout as well as Alternative Advancedment (AA) options starting at Level 51 which allow you to accumulate points that enhance your character by diverting some (or all) of your regular experience to individualizing your character.
Like to play in groups? Get LDON expansion when you get to level 20 and you could spend all of your time in groups since adventures require a min. of 3 people. Before that there are the group zones like Crushbone, Orc Alley in Oasis, Splitpaw in S. Karn, etc.
Want to solo? All characters can solo early in the game, but you will want to check which ones do better at this in the higher levels - Clerics for example are not good solo in higher end game.
Want to explore different areas? I have been playing for a couple of years and still have a lot of zones I have never been in.
Like to cast magic? Combat? A little of both? - there is a wide range of character classes that allow you to fit your play style easily.
I would suggest buying Evolutions first and added expansions later.
Overall, this game has a lot of flexibility so sit back and enjoy the ride. Good Hunting and welcome to EQ