As you want to start preparation for RRB Section Engineer Exam, so you should follow these tips:

Have detailed syllabus and important notes

Download previous year question papers.

Make a Schedule for study

Solve Mock Tests also.

Use short tricks and make short notes of important topics.

Here I am providing syllabus of RRB Section Engineer Exam for your reference. You will start preparation for syllabus:

RRB Section Engineer Exam Syllabus

General Intelligence and Reasoning Syllabus
Number Series, Input-Output, syllogism, Coding-decoding.
Coding & Decoding, Arithmetic number series, non-verbal series, Statement conclusion.
Decision making, Direction sense test, visual memory, Blood relations, figural classification and arithmetical reasoning.
Similarities and differences, space visualization /orientation, analogy.
Word Building, Clock, Seating arrangement, Calendar.

Arithmetic Syllabus
Algebra.
Ratio & Proportion.
percentage
Profit & loss.
Data Interpretation.
Interests.
Time and distance /work.
Mensuration.
Age problems.
Pipes & Cisterns.

General Awareness Syllabus
General Awareness on Railway.
New Technologies & Reform in Indian Railway.
Rail Budget.
Indian – History, Geography, Polity, Economy Current Affairs, Sports, etc.

Engineering Subjects:

Electrical Engineering Syllabus
Electrical Machines.
Electrical and Electronic Measurements.
Analog & Digital Electronics.
Signals & Systems.
Power & Control Systems etc.
Basics of Circuit & Power Electronics.
Circuits & Measurement Systems.
Electrical Machines.

Electronics Engineering Syllabus
Electronic Devices.
Energy bands.
Wireless Communication.
Diodes.
Communication.
EMFT.
Control System.
Signal & Systems.
Tunnel.
Analog and Digital Circuits.
Basics of Signal & Systems.
Junctions.
Carrier transport in silicon: diffusion current, drift current, mobility, and resistivity.
Generation aand recombinationof carriers.

Computers Engineering Syllabus
Computer Fundamentals.
MS Office.
Information systems.
Operating systems.
Computer Networks.
Network communication.
Web technology & programming.
Languages.
Software Engineering
DBMS.
Algorithms.
Database.
System programming.

IT
MS Office.
DBMS
System programming.
UNIX.
Data & Network communication.
Software Engineering.
Environment & Pollution Control.
C , C++ & Java language.
Operating systems.
SAD
Web technology & programming.
Information systems.
Computer fundamentals & organization.

Instrumentation & Measurement Engineering
Basics of Measurement Systems.
Analog /Digital Electronics.
Process Instrumentation.
Transducers.
Mechanical Measurement.
Circuits.
Industrial Instrumentation.

Civil Engineering
General Civil Engineering.
Costing.
Valuation.
Building Materials.
Soil Mechanics.
Concrete Structures.
Steel Structures.
Water requirements.
Highway Planning.
Surveying.
Coordinate system.
Environmental Engineering
Estimating.
Mechanics.
Structural Analysis.
Hydrology.
Traffic Engineering.
Hydraulics.
Construction.
Projections.
Measurements of distance and directions.
Errors and adjustments.
curves.
Construction /Structure Engineering and drawing.

Mechanical Engineering
The Strength of Materials.
Kinematics of Machine.
Fluid Mechanics.
Steam Tables.
I.C. Engines cycles.
Machining and Machine Tool Operations.
Metrology and Inspection.
Theory of Machines.
Heat Transfer.
Thermodynamics cycles.
Casting.
Thermodynamics.
Power Engineering.
Engineering Mechanics.