I've been playing these types of games since commodore 64 and vic20s and the original settlers game.

As a newbie I've noticed that the lower lvls of this game has an impossible task, at 100 points you have no one to attack, because the retention of newbies is really poor, so no vespene, apart what you can manufacture, which lets face it is nominal, the pirates are pretty far away with no chance to get vespene. So you have to log off and come back, if you can be bothered, guess what biggest majority don't find it interesting enough to be bothered.. 

All I can say the makers must be making a fortune, because if you don't have a regular turn over of newbies, the game will go the same way as others.

Get colonization tech asap and move to an area with some big inactives. Doing that will give you the boost you need to get through the low ranks until you can start competing with other players. https://xcraft.net/forum/topic_20256 The second post of this guide can help you pick a nice planet and if you need help finding a nice place to settle message me in-game and I'll be happy to help you find a good spot. I plan to abandon my starting planet tomorrow now that I have other planets going strong. 

I'm new at this game and the mentor that was appointed to me (@Victoria) is not answering my questions. She might receiving some HC for my developments but it would be nice to receive some info.
I even don't know how to change her.
First of all, I search for someone that has some experiënce and some time to explain some stuff to a newbie (and at least answering pm's).
I already made several mistakes by lacking knowledge.
Who wants to be my mentor?

Newbies can message me for mentoring if you like. I don't claim to know everything but I have managed to help quite a few people learn the game enough to continue on and make something of it.  

 Any newbie can message strong players around them to ask for advice or help, or even to ask to be a recruit. Most people are friendly here, and changing mentor is easy to do. This way the person giving you advice is the person who gets the small reward for being a mentor.