Rule 1 (the most important in my book) DONT BEG! If you beg for subs, views, ect nobody will watch your videos and you wont get subs
Rule 2 Make quality content, this means at least 720p HD, little or no lag, and cool effects if you want
Rule 3 make your videos interesting, this means either commentating or adding fitting music as well as choosing interesting topics. One thing you probably want to stay away from is lets plays, they are way (I MEAN WAY) overdone so try something new.
Rule 4 Form a schedule, let people know what videos you plan to upload and when so they will have to come back for more
Rule 5 Upload regularly, upload at keast 2-3 videos per week more if possible, also dont just out of the blue stop uploading for a month (I have done this and it doesnt work out) if you need or want to stop uploading for awhile let your fans know when you will stop, how long you will be gone, and why you are stopping.
Thats about all I can think of so I hope these tips help you out.