hey Andre, a belated welcome to the rough and tumble of the forums mate!
I have a few points to make on this one. When I first read your thread yesterday my instinctive reaction was to move it straight to the videos and links board, as the sentiment of your first post worried me a bit and I was anticipating you copping some flak. But you are a young, enthusiastic guy - and a good player too, I might add - and I really want to encourage you, not discourage you. Yes I did take up your request and have subscribed too. Your 'Sweet Home Alabama' rendition is REALLY GOOD!
My suggestions/advice , for what it's worth...
1. The UU is primarily a community, a family, of folks pursuing and sharing in our love of the ukulele. There is certainly, and rightly perhaps, a kind of 'scratch my back and I'll scratch yours' mentality that exists with the youtubers and people who post videos on the boards. Ken is right in that to receive love, you do really need to give some as well. There have been other members whom I have read complaining / questioning why people posting the 50 thousandth dodgy cover of 'I'm Yours' get 100's of views as opposed to someone writing their own great songs receiving little more than a dozen. Usually the reason is because those people haven't spent time investing in others, in giving them words of encouragement and praise. I think you'll find when you begin to do that, you become a part of that community and form some great friendships as well...it is then that your support base will begin to grow.
2. Your OP is a little uncomfortable to read for two reasons. (i) it unfortunately does come across as 'begging', but more importantly (ii) in choosing those words you are almost devaluing your music...saying "PLEEEEEEZ subscribe". You need to give people a reason to subscribe, for as John said, people tend only to do that when they feel they are going to hear some good playing that will inspire and motivate them on their own uke playing journey. Your playing alone stands on it's own two feet...
So why don't you head over to the 'Videos and Links' board, post one of your videos, and perhaps underneath leave a comment to the effect of...'if you like this performance I would appreciate your subscribing to my channel'. Be proactive about it and leave a positive footprint, rather than putting pressure on folks which may make them turn their head the other way. I think your responses would be much more positive. Then, while you're over there, watch some other members' clips and leave some kind words for them. Because it really works both ways.
3. Lastly and most importantly it would be helpful for you to ask yourself ' What is my motivation for starting a youtube channel'? If it's to become rich and famous then you have a lot of competition! There are thousands of videos posted worldwide each day, and there are only a handful of ukulele players who can legitimately call themselves professionals. If on the other hand your motivations are more along the line of sharing your love of music and simply doing it for the sake of what you love and are passionate about, you will get much more enjoyment out of the process and are less likely to be disappointed. Subscriptions are hard earned things and it takes time to build up a following.
Sure there are shortcuts...every other day there seems to be a message in my inbox from someone directing me to a site designed especially around the principle of getting you lots of subscriptions and views. If that's really what you want then I could pass on some of those links to you. But I would rather not do that myself, I would rather maintain my integrity.
I think it's great you want to see your little sister grow as a player and want to help her Andre. I also think you have a lot of talent yourself mate, as your clips make that very obvious. I really look forward to watching you develop as a player and become more involved as a member of our online forum community. Just remember bro, subscriptions are NOT the gauge of how good a player or person you are.