I am already found my broker and work with them for more than eight years, so far so good and no problem, this company regulated in ASIC, FCA, and Cysec, namely FXOpen broker, about spread in my view also included low or competitive spread, especially pair USD included XAUUSD.
Speaking about safety measures, then I guess you should determine whether a potential broker a scam or not. It's kinda easy to determine, you just need to check licenses and apply to customer support. Often customer support give you the understanding that you would better stay off a broker. It replies too long and pretty rude. Scammers don't care about customer support, hence it's awful. Moreover, you have to check withdrawal and depositing process. Actually, there are no issues with depositing, while there might be some troubles with wthdrawals in case of scam. Check these things and make some conclusions.
First you have to see whether the broker is regulated and licensed or not. If not regulated and licensed, move to another one. Then check the facilities you want for your trading like deposit method, spreads, leverage etc.
There are lots of measures which you need to choose a broker in order to trade safely. For example, you ought to check all the information about your broker mostly because you need to be convinced that everything is okay with and it's not a scammer. There are several ways how to do it. Forstly, you have to check all the information concerning regulations,licenses and certifications. Secondly, you should check client service from a certain broker, how fast they reply, how polite are they and something liek that. Finally, you should check that there are no issues with withdrawing and depositing money.
The main safety measure is to convince that your broker might be considered as a reliable one. I believe that there are sveral ways how to determine a proper broker. For example, I always chekc three main things in my opinion, which can determine whether a broker is reliable or not. These things are the work of customer support, processes of withdrawing and depositing money, and the presence of regulations and certifications. I think you have to check these things before pick a particular broker as your primary, maybe it isn't the same as you got used to think.