DS1 is 11 and has a touch of anxiety relating to perfectionism but I'd describe him as emotionally/mentally healthy overall - he deals with day to day things very well, his anxiety manifests over starting new situations or going to new places or getting things exactly right (like following homework instructions to the letter). To be honest nothing out of the ordinary that most people wouldn't feel anxious about! He makes friends easily, is kind and thoughtful (when he's not stuck in a preteen stubbornly self-centred mood anyway), able and willing to attempt new things and problem solve when things go wrong (most of the time.)
Obviously he could just be like that :) But I do think there are a couple of things I've done that have felt very important to me and I'm trying to do for DS2 as well. (He's just 1 - huge gap!)
I have always made a point to accept and validate feelings/emotions. There is a great book called How To Talk So Kids Will Listen and Listen So Kids Will Talk which explains a lot about this approach. There is also a Little Kids version which is specifically for parenting children aged 2-7 (The original is better for 4-12, although useful for any age.) The information in them both is good. I think the little kids one is a bit more modern and accessible. There's another parenting approach I've come across recently called RIE, the most well known proponent being Janet Lansbury (You can follow her on Facebook and she has a great free podcast). This approach also stresses the importance of accepting our children's emotions, even the ones we find stressful. The book and the RIE materials explain that we often want to "fix" our children's feelings, so tell them "Ssssh, it's OK, don't cry" or distract them out of being upset, or try to reason with them "Hey, I'll be there in a minute" - you can even find yourself saying stuff which outright dismisses negative feelings like "It's not that bad, don't make a fuss" "That's enough [crying or whining]" "Come on, be a brave girl" etc. The approaches I've followed suggest that it's better if you don't do that but instead give the child space to work through their feelings and say things like "Oh, that sounds like a hard day" or "That was a bad fall!" Anger I've found harder to work with, but I think it's quite important, especially for girls (girls are often inadvertantly taught that anger isn't acceptable, when what we mean is that aggression isn't acceptable. It is useful to note the difference.)
OTOH I would definitely advise to wait and see how they react and try to be neutral before they do! For example for a fall in the park if you rush in with "Oh my poor baby how is your knee, are you bleeding?" it is likely to upset them more whereas if you wait to see their reaction, they will often just get up and carry on playing! But in general the idea is that we can be quite afraid of our children being upset almost and we want to make it better all the time. But by letting them be upset and work through it, they learn how to sit with difficult, uncomfortable feelings and that it's safe and natural to have to work through them. Also, I am a believer that if you listen sincerely to the little problems (a biscuit breaking IS a heartbreaking ordeal when you are two) they will trust you to listen to their big problems later.
We are now getting the start of hormonal mood swings, and sometimes I just reflect it back to him "You sound angry, has something annoyed you?" or if the effect is (to my ears) slightly comical, like his ranting about his maths book the other day (he was outraged that it had the audacity to set a question he deemed unanswerable) I just took a jokey tone and said something like Hey, what has this poor book ever done to you? It's just living its life as a failed tree and now it gets some hapless teenager ranting on at it! Poor book! Let's have a look at this question. He finds that funny and it can help him look at his own reaction and see that yes, it's a bit out of proportion to be so annoyed at a stack of paper. But we have also talked about mood swings and how they can sometimes make feelings feel a bit out of proportion.
I have also always tried to treat him with respect and speak to him, not as an equal exactly because I understand that I am an adult with responsibility for him, not to mention 20 years of life experience and maturity over him, but I have never gone in for parenting where I say jump and expect him to say how high. It's more like our family is a team and I (and DH once he came into our lives) are the team leads. In certain cases we make decisions and that is final but generally we are open to negotiation and discussion and this is really coming into its own now DS1 is getting older. I've always approached all issues with a "simplified version of the facts" approach even when we've faced some really tough topics like his father being absent due to being a general knobjockey, elderly family members passing away, even a friend dealing with childhood cancer (thankfully now cancer free). So he knows that we don't lie to him or bluff him off and (I hope) it means he's not afraid to talk to us about tough stuff. I'm trying to make time for real conversation as often as possible now he's getting older and wanting to hole himself up in his room and play games or spend time with his friends. Actually this paragraph has just reminded me of an old parenting website I used to go on called TCS - Taking Children Seriously.
I also think friendship groups are hugely important in the teen years and (from my own experience) having several potential "pools" of friends. So for example, school friends and then doing an activity (or two) where they meet a different group of people, or family friends where you get together and your kids know each other. This is a long way off for you yet but I found it massively helpful during my teens when one of my friendship groups was turbulent and full of in-fighting (which happened periodically) to be able to turn to the other and get support there. I would say even more so today considering they all have whatsapp groups etc to keep in touch at all times, which can be stifling. Incidentally we were four girls and one boy in one of these groups and the one boy was frequently baffled by all of our constant friend dramas - apparently teenage boys don't tend to do that so much.