good luck man, whatever niche you picked is definitely a good one. Work hard on scaling that up and you will make some nice cash in no time.
My advice for you is under no circumstance should you buy views from fiverr. If anything, they will harm your video as most are low retention and poor quality views. It may seem like a good investment due to the low price, but you get what you pay for and it's nothing good.
I would say buy high retention views from viralsocials, I believe his BHW name is 'skittles' or something and he should have a thread in the BST forum. I have always had great experience with these and they are cheap, being around $5 for 10k high ret views and he always over delivers by a lot (90-100%) high retention views are worth MUCH MORE than regular views and you will definitely notice rank increases afterward, just don't spam them on all at once, do increments of a 1000 every day or two and slowly build it up
I would advise to re-invest all your profits back into your videos at the start, even if you don't make a profit back, you will learn what not to do and the experience will be much more valuable than the few dollars spent. Also, don't be cheap with a domain and hosting - it's only like 10 bucks and your conversion rate will be much higher if you incorporate a widget and a nice looking web page
I suggest focusing on high ret views > comments > likes > favourites > subscribers in that order
Also, once you start seeing money coming in nice after all your hard work - don't give up and don't get lazy, at one point or another Youtube will take down your video and it sucks when your earnings drop significantly overnight
keep working on new videos and make sure you use ccleaner before logging between accounts, or you are just creating a footprint and it's not uncommon for many accounts to be banned at once. Only upload 2 videos per account and private proxies would be a good idea too once you are making serious cash (i never used them but it would help)
for free likes, use an imacro on addmefast. DEFINITELY look into this, you can find some good addmefast imacros on BHW if you use the search and it will be an incredibly good use of about 20-30min to download and set it up in your browser. You can get around 100-200 likes an hour by doing this and you can have the macro going on auto-pilot while working on videos through another browser.
For comments I would suggest enhanceviews, I like to post custom comments to gain credits because you get like 400 or something per successful comment and that equates to a few comments for yourself once you spend the credits. When you spend credits, do the 'custom' comment option and make them all high quality and relevant but not too over the top, maybe throw in some neutral comments to so that it looks more realistic
always try out new twists on your existing niches and keep trying new ones. I would avoid the super saturated ones until you know how to properly rank and stand out from competition
One thing that I suggest the most though is the learn good site SEO and focus on gaining traffic through search engines as opposed to youtube. You have a much less chance of losing your traffic than on youtube and most big earners that I know focus solely on websites and SEO for their traffic. It will take awhile but it will definitely be worth it.
good luck.