I feel like a A+ is kinda irrelevant doing helpdesk. imo, here is some direct information and skills you need so you want be wasting your time learning
1.Try and find out what ticketing system the company uses, ServiceNow, Remedy, etc. try to familiarize with the system, because you will be using that 100% of the time . Find some youtube tutorials or download spiceworks ticketing system to practice
2. learn Office 365 and how to troubleshoot the suite!!! (pluralsight videos )
3. Learn how to remote desktop, basic active directory, I recommend some win7/ 10 pluralsight videos
4 Practice on your typing speed and customer service phone skills ( Remember you may be on the phone all day talking )
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Basically man all you will doing is making tickets, escalating tickets and troubleshooting over the phone