I'm working on my instrument rating and wondering if I can practice ILS approaches without an instructor? Using a safety pilot, also not instrument rated, could I call approach stating VFR would like ILS into X. Or do I just call the tower and ask for it there? Or can I only do this with an instructor?
Sure you can! There's nothing wrong with shooting practice approaches if you're not instrument rated (in the US, at least) as long as you don't actually accept an IFR clearance.
You would probably be better off asking approach control for practice approaches rather than tower, if you have approach available to you.
Yes, you can request practice approaches under VFR, however you or a safety pilot needs to take over airspace monitoring if you put on an IFR hood.
Unless your question is FAA specific, here are some excerpt from the German AIP.
562 VFR-PRACTICE APPROACHES
562.1 A practice approach may be approved for VFR-flights intending to use an instrument approach procedure for training purposes.
562.2 When giving heading and altitude recommendations during VFR-practice
approaches, it shall be explicitly emphasised that it is a suggestion.
562.3 If appropriate, altitude information shall be provided to ensure compliance with the minimum safe height.
And also the associated phraseology to request:
A: REQUEST (type of IFR approach) PRACTICE APPROACH VFR
G: (type of IFR approach) PRACTICE APPROACH VFR APPROVED / NOT APPROVED
This is covered in Aeronautical Information Manual (AIM) 4−3−21. Practice Instrument Approaches and makes several references to 14 CFR part 91 -- mostly for VFR flight. Here is the important part:
Pilots not on IFR flight plans desiring practice instrument approaches should always state ‘practice’ when making requests to ATC. Controllers will instruct VFR aircraft requesting an instrument approach to maintain VFR. This is to preclude misunderstandings between the pilot and controller as to the status of the aircraft.
For some uncontrolled airports, ATC cannot service practice IFR approaches.
Once cleared for the approach, ATC will assume responsibility for IFR and VFR separation as IFR. Just as with IFR flight plans, some diligence is required by pilots to avoid pattern traffic at uncontrolled airports.
This section is fairly detailed with 11 subparagraphs. The complete AIM is available from https://www.faa.gov/air_traffic/publications/