One way to promote your portal is to set up an online advertising campaign.
When setting up an AdWords campaign, you can define the countries you want to target and search keywords you want to use. You will only pay when people click on your ad, and you can choose to pay per click or set a daily maximum budget for your campaign
The most common online campaigning mechanism is Google AdWords, where Google users who search for a specific keyword related to your portal (e. g. “Research in Estonia”) will see your advertisement on the right-hand side of their browser window.
When setting up your Google campaign, you can also consider Google AdSense, where your ads will be displayed directly on websites related to your content.
Another possibility, especially if you have a EURAXESS Facebook page, is to advertise your portal on Facebook. Here as well, you will define the target audience who will view your ad. Unlike in Google, in this case you can use the data people have entered in their Facebook profiles, e.g. their age, universities they have attended, their interests, etc.
The most complex part of online campaigning is monitoring the results and making changes in your campaign according to that outcome, since the advertising mechanisms that online campaigns use are quite complex. It might be a good idea to consult an Internet marketing company for your campaign to be a success.