Hello my friend:
While we are Ebonheart Pact, you can be any alliance in the guild. You will be able to group and interact with any member in any non-PvE zones. Only in the PvP events, you will not be able to join the guild if you are another alliance. We typically may have 2 events a week that is in PvP zones.
Common mistakes / advise:
Always makes sure you are eating food or drinking drinks for the buffs. This helps tremendously.
Use potions when needed. Don't be stingy as you level since you will find more "cheap" potions along the way. I wouldn't go making too many potions to use since you are going to out level those potions quickly and it eats up supplies. I would just use the standard potions you find in the world. Exception is if you are leveling in alchemist.
The main quest at the Harborage, people do not realize you can port there using the wayshrine.
To save money traveling, always either port to a player or use a wayshrine. No point porting to a place using a map.
Ask for someone to craft you a "set" armor to give you nice stats to assist in leveling.
Its always best to have one bar of skills (when you have weapon swapping) to use for leveling. Meaning that bar of skills that isn't maxxed out. Prior to turning in quest, you flip to the skill bar to level all the skills at once. Another technique is to have at least 1 skill on the bar to level up at all times when fighting.
Training gear is great for leveling up quicker if you wish.
Completing main story line and some zone quests will give skill points.
Click all the glowing books on the grounds / tables - some will give experience for the mage skill line.
Click all the book shelves - some give experience for other skill lines.
Finding and clicking 3 skyshards will give a skill point.
At the moment, do the holiday event, and use the whistle/skeleton form for double experience. It will only last until the end of the month.
For stats, unless you are a tank, you should stack majority of your stats towards Stamina or Magicka depending which direction you wish to go for maximum effect. Do not spend any points in the other attribute since that will gimp your dps. Putting a few points in health is helpful.
Make sure your gear has enchantments to obtain additional bonuses. Players can craft those as well.
Make sure your weapon enchantments are charged up. You only need to recharge the weapon when it's enchantment runs out of power.
If you going to craft, suggestion is not to do all the crafts on one character. Put the armor traits (light, medium, heavy) on one character and the other crafts on another since skill points are limited, especially early on. Although Alchemy and Provisioning has some useful skills to make the food/drinks/potions last longer. Always research items when you can since they are timers.
If you have any additional questions, please feel free to contact me in game or in discord. I usually am on at various hours of the day.