I think you don't need, the rating system do that for you, if you trade good and if you have good rating, in the first 5 or 10 Signals, people will found you and subscribe to you.
In case of MQL5 portal so - in your profile and in the blogs.
Concerning external sources so I made few posts some time ago with the explanation about:
Forum on trading, automated trading systems and testing trading strategies
How to Start with Metatrader 5
Sergey Golubev, 2017.01.09 06:38
Do you sell something on the Market? Are you signal provider? So, just some links about promotion:
Sergey Golubev, 2017.01.09 06:37
And just want to remind that the promotion of signals and market products is prohibited on the forum sorry.
One way to promote your signal is to create any external blog and place a widget there:
MetaTrader 4 and MetaTrader 5 Trading Signals Widgets
This is the my personal example with my google blog:
Sergey Golubev, 2013.06.23 11:51
I installed widget (Top Signals) for my google blog in easy way using this link for example so everybody can do it (widget for some particular signal or signals, or widget for some broker). I did not place it on some other websites because I am not a signal provider and I am not market vendor. But I think that google blogs' promotion as a widget (together with simple promotion using facebook, twitter and google+) are fully enough to get some subscribers/clients.
But if some signal provider (or Market vendor) wants to get many subscribers/clients so it may be necessary to go to more quick way - go to the other Metatrader forums to promote your signal or product in direct way - just my experience.
It is normal, you still new and you have big Drawdown, try to trade good with minimum Drawdown and wait some time to have good history.
To get more subscribers, you do not need to advertise your signal. Advertising does not help you. To get more subscribers, you need to sell well on Forex. It sounds trite, but it's true. The life of your account should be more than one year. Each month should be profitable - about 5-10%. Drawdown should be less than one third of the deposit, that is less than 33%. You must put a stop loss. The Sharpe ratio is at least 0.1. In this case, you do not need advertising. The parameters of your account are your advertisement.
Yes, it is difficult, but there is no other way. All our life is overcoming difficulties. We are helped by the belief in achieving success. Trading is a matter of faith. We believe in our trading system.