Small Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Total 5000; Flight Crew Type 500
Confusion; Situational Awareness; Troubleshooting
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Airport; Environment - Non Weather Related
Received ATIS and requested taxi clearance with VFR Flight Following. Instructed to taxi to runway 35R via the ramp and cross Runway 35L. Started the taxi and received the VFR Flight Following instructions on the taxi. During taxi I was looking for the ramp taxiway lines; unable to see them due to fading. Entered Runway 35L; with no knowledge of crossing a hold short lines.  There is no difference between ramp and Runway 35L concrete and the ramp was covered in weeds.  Cleared the runway at 35L and asked for instructions from Tower to Runway 35R. Was instructed to taxi down Runway 35L to Taxiway G then holdshort of Runway 35R.
Corporate Pilot reported Runway Hold Short lines are faded.