Your best Forex signals will likely have a way of figuring out where your trade could go, where it can be good to open a trade and where to close it, for making profitable trades consistently. This is what you should expect from good quality signals:

You'll need to have some sort of explanation and a very in-depth guidebook of where the system applies.

Would they work with any type of market or there are constraints

Will they be suitable for all currencies, otherwise, you have to know precisely what currency pairs it's relevant to

Are they likely to work with all trading sessions or there are exceptions for European or American sessions

Are there any exceptions and alerts

Test! Test! Test! Never ignore the value of testing and never just blindly believe the signal producer's data. Try it on demo account and check it will produce final results persistently. You should be willing to count on your forex signals with a relatively big rate of success. Make sure you test and drill it on historic data if it's possible (unless signals only give live data, which is not possible to test on historic charts). The more historic data you will have, the more you can rest assured that a specific signal is solid.

You have to determine the maximum loss that happened using these signals and use it along with your money management plan. If you are sure that historically, signals never lose more than 10% of the deposit, you may make reliable trades with greater quantities than if you see that signals might occasionally give 20 or even 30% loss. You may have unique money management policies so you should adopt accordingly.

The best Forex signals are likely to cover multiple circumstances on the Forex market. You should be positive it'll perform in the up market, down market or side market (flat) or at least have a very good description plus a disclaimer what market these particular Forex signals are good for. For instance most Forex trade signals are going to include all major currencies like GBP, USD, and EUR all the time the market is open or have some very particular trading conditions and disclaimers clearly written.

To get the full value of your forex trade you must know what is happening in regards to all the major currencies, because in many cases a lot of currency pairs are closely correlated. Pairs like EUR/USD, JPY/USD, CAD/USD are closely related, because all of them have a USD as one of the components, so you can use many correlated currencies as confirmation for your market entry and exit points.

If you use the best FOREX signals, it really is fairly easy to guide your trading in this market and take away any threat and mystery around FOREX trading. If you use high quality signals, it is easy to invest accordingly, because somebody else has been doing analysis to suit your needs.

Any wise individual should understand, that no signals and no system can promise 100% reliability under all market conditions. In fact, I would say the opposite is true. You know for certain that you will be loosing money on occasion and your emotional citadel must be ready for this.

However after all said and done, it is worth trusting a reputable 3rd party, since the advantages will surely outnumber the drawbacks.

To start with, any good third party offering Forex trading signals is attempting to make sure they are doing a damn good job with it.

If they will not, they can loose their clients faster than they can sneeze and may also have a couple of lawsuits in the process. They are interested in keeping the signals worthwhile for clients and refining it as much as they can.

Another thing to consider is, that many people creating the trading signals may also be using the same signals for entry / exit instructions themselves.

This means that any serious problems in the signals will reflect on both themselves and their clients and that will leave them with no money real fast.

They're doing all they're able to to prevent this, so if the signals you're using are proven, you will be reasonably sure it'll continue to generate good signals in the foreseeable future, since owners are keeping tabs and improving the system constantly as Forex conditions change in the market.