It is absolutely necessary to observe that you

file for an application of the correct trademark,
properly file for an application of the trademark,
have the trademark speedily registered,
enforce the registered trademarks rigorously,
monitor on-going your own trademarks,
contest external trademarks on time,
defend your own trademarks in a strategically clever way.

It is often sensible to already engage the patent attorney before the filing for application of the trademark because he can advise in advance when you are finding a trademark.. At this stage you can often save a lot of money by avoiding typical mistakes.

When filing an application for a trademark, a frequent mistake occurs in that the applicant restricts by himself unnecessarily the scope of protection of the trademark by its imaging (adding of not absolutely necessary pictures or wording parts).

In opposition proceedings, it is generally good to negotiate with the opposing party, whereby the duration of the proceedings can be considerably shortened.

Not enough importance is often attached to monitoring the trademark and the defence against similar more recent trademarks. Hereby it is often forgotten that your own vested rights are diminished by a lot of similar more recent trademarks (problem of watering-down).